Removable tip for laser device

ABSTRACT

The present invention provides an improved method of measuring analytes in body fluids without the use of a sharp. The method having the steps of irradiating the skin of a patient by focused pulses of electromagnetic energy emitted by a laser. By proper selection of wavelength, energy fluence, pulse temporal width and irradiation spot size, the pulses precisely irradiate the skin to a selectable depth, without causing clinically relevant damage to healthy portions of the skin. After irradiation, interstitial fluid is collected into a container or left on the skin. The interstitial fluid is then tested for a desired analyte to approximate the analyte concentration in other body fluids. Alternatively, after the forced formation of a microblister, the epidermis covering the microblister is lysed and the interstitial fluid is subsequently collected and tested.

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/083,088, filed on Feb. 26, 2002, which is a continuation ofU.S. patent application Ser. No. 09/443,782, filed on Nov. 19, 1999, nowabandoned, which is a continuation of U.S. patent application Ser. No.08/955,982, filed Oct. 22, 1997, now issued as U.S. Pat. No. 6,056,738,and which is a continuation-in-part of U.S. patent application Ser. No.08/792,335 filed Jan. 31, 1997, now abandoned, which is acontinuation-in-part of U.S. patent application Ser. No. 08/126,241,filed on Sep. 24, 1993, now issued as U.S. Pat. No. 5,643,252. All ofsaid applications are incorporated herein in their entirety by referencethereto.

FIELD OF THE INVENTION

[0002] This invention is in the field of medical procedures, namelylaser medical equipment used to perforate or alter tissue for monitoringanalyte concentration in body fluids.

BACKGROUND

[0003] The traditional method of measuring blood glucose, or otheranalytes, consists of taking a blood sample and then measuring theanalyte concentration in the blood or plasma. The blood is typicallycollected from a patient utilizing mechanical perforation of the skinwith a sharp device such as a metal lancet or needle.

[0004] This procedure has many drawbacks, including the possibleinfection of health care workers and the public by the sharp device usedto perforate the skin, as well as the cost of handling and disposal ofbiologically hazardous waste.

[0005] When skin is perforated with a sharp device such as a metallancet or needle, biological waste is created in the form of the “sharp”contaminated by the patient's blood and/or tissue. If the patient isinfected with blood-born agents, such as human immunodeficiency virus(HIV), hepatitis virus, or the etiological agent of any other diseases,the contaminated sharp poses a serious threat to others that might comein contact with it. For example, many medical workers have contractedHIV as a result of accidental contact with a contaminated sharp.

[0006] Post-use disposal of contaminated sharps imposes both logisticaland financial burdens on the end user. These costs are imposed as aresult of the social consequences of improper disposal. For example, inthe 1980's improperly disposed biological wastes washed up on publicbeaches on numerous occasions. Improper disposal also permits others,such as intravenous drug users, to obtain contaminated needles andspread disease.

[0007] There exists an additional drawback of the traditional method ofusing a needle for drawing fluids. The pain associated with beingstabbed by a the sharp instrument can be a traumatizing procedure,especially in pediatric patients, causing significant stress and anxietyin the patient. Moreover, the stabbing procedure often must be repeatedbefore sufficient fluid is obtained. For analytes that need to beconstantly monitored, patients may not comply with the frequency ofmeasurement due to the pain involved. In the case of diabetics, failureto measure glucose levels can result in a life-threatening situation.

[0008] In addition to blood withdrawal, concentrations of analytes ininterstitial fluid can be measured for accurate representation ofanalyte concentration in the blood. Because of the strong barrierproperties of the stratum corneum, however, collecting interstitialfluid through the stratum corneum poses problems. To reduce the barrierfunction of the stratum corneum, a number of different techniques arepresently used, these include: (1) using a metal lancet to cut the skin,(2) chemical enhancers, (3) ultrasound, (4) tape stripping, and (5)iontophoresis. Chemical enhancers pose the problem of potentiallyreacting with the analyte to be measured. Moreover, the time lapse afterapplication to propagation of interstitial fluid is great. Tapestripping is unsatisfactory because of the pain to the patient.Iontophoresis and ultrasound, similarly have drawbacks in the collectiontime and the quantity of fluid removed. As previously discussed, the useof a metal lancet has the drawback of patient discomfort and thepossibility of contamination.

[0009] Thus, a need exists for a method to easily measure theconstituents in the blood or other body fluids, without: (I) the use ofa sharp object, (2) the slow speed of fluid collection, or (3) the paincurrently associated with the elimination or reduction of the barrierfunction of the stratum corneum. The method would further obviate theneed for disposal of contaminated sharps and eliminate the painassociated with sharp instruments. The desired method would also,ideally, increase patient compliance for monitoring the desired analyte.The method and apparatus disclosed herein achieves these and othergoals.

[0010] Lasers have been used in recent years as a very efficient precisetool in a variety of surgical procedures. Among potentially new sourcesof laser radiation, the rare-earth elements are of major interest formedicine. One of most promising of these is a YAG (yttrium, aluminum,garnet) crystal doped with erbium (Er) ions. With the use of thiscrystal, it is possible to build an erbium-YAG (Er:YAG) laser which canbe configured to emit electromagnetic energy at a wavelength (2.94microns), among other things, which is strongly absorbed by water. Whentissue, which consists mostly of water, is irradiated with radiation ator near this wavelength, energy is transferred to the tissue. If theintensity of the radiation is sufficient, rapid heating can resultfollowed by vaporization of tissue can result. In addition, oralternatively, deposition of this energy can result in photomechanicaldisruption of tissue. Some medical uses of Er:YAG lasers have beendescribed in the health-care disciplines of dentistry, gynecology andophthalmology. See, e.g., Bogdasarov, B. V., et al., “The Effect ofEr:YAG Laser Radiation on Solid and Soft Tissues”, Preprint 266,Institute of General Physics, Moscow, 1987; Bol'shakov, E. N. et al.,“Experimental Grounds for Er:YAG Laser Application to Dentistry”, SPIE1353:160-169, Lasers and Medicine (1989) (these and all other referencescited herein are expressly incorporated by reference as if fully setforth in their entirety herein). Laser perforators of the type explainedin U.S. Pat. No. 5,643,252, said patent being incorporated by referenceherein, have generally been designed to perforate or alter the tissue ofa patient to reduce the barrier function of the stratum corneum, thusallowing for transport of fluid through the target tissue.

SUMMARY OF THE INVENTION

[0011] The present invention employs a laser to perforate or alter theskin of a patient for removal and subsequent analysis of interstitialfluid. These measurements can then be used to approximate analyteconcentrations in other body fluids, such as blood. Prior toapplication, the care giver properly selects the wavelength, energyfluence (energy of the pulse divided by the area irradiated), pulsetemporal width and irradiation spot size so as to precisely perforate oralter the target tissue to a select depth and eliminate undesired damageto healthy proximal tissue. After perforation or alteration,interstitial fluid is allowed to propagate to the surface of the skinfor collection and testing.

[0012] According to one embodiment of the present invention, a laseremits a pulsed laser beam, focused to a small spot for the purpose ofperforating or altering the target tissue. By adjusting the output ofthe laser, the laser operator can control the depth, width and length ofthe perforation or alteration as needed, such as to avoid drawing bloodinto the interstitial fluid sample.

[0013] In another embodiment, continuous-wave or diode lasers may beused to duplicate the effect of a pulsed laser beam. These lasers aremodulated by gating their output, or, in the case of a diode laser, byfluctuating the laser excitation current. The overall effect is toachieve brief irradiation, or a series of brief irradiations, thatproduce the same tissue permeating effect as a pulsed laser.

[0014] The term “perforation” is used herein to indicate the ablation ofthe stratum corneum to reduce or eliminate its barrier function. Theterm “alteration” of the stratum corneum is used herein to indicate achange in the stratum corneum which reduces or eliminates the barrierfunction of the stratum corneum and increases permeability withoutablating, or by merely partially ablating, the stratum corneum itself. Apulse or pulses of infrared laser radiation at a subablative energy of,e.g., 60 mJ using a TRANSMEDICA™ International, Inc. (“TRANSMEDICA™”)Er:YAG laser (see U.S. Pat. No. 5,643,252, Waner et al., which isincorporated herein by reference) with a beam of radiant energy with awavelength of 2.94 microns, a 200 μs (microsecond) pulse, and a 2 mmspot size) will alter the stratum corneum. The technique may be used fortransdermal drug delivery or for obtaining fluid samples from the body.Different wavelengths of laser radiation and energy levels less than orgreater than 60 mJ may also produce the enhanced permeability effectswithout ablating the skin.

[0015] The mechanism for this alteration of the stratum corneum is notcertain. It may involve changes in lipid or protein nature or functionor be due to desiccation of the skin or mechanical alterations secondaryfor propagating pressure waves or cavitation bubbles. The pathway thattopically applied drugs take through the stratum corneum is generallythought to be through cells and/or around them, as well as through hairfollicles. The impermeability of skin to topically applied drugs isdependent on tight cell to cell junctions, as well as the biomolecularmakeup of the cell membranes and the intercellular milieu. Any changesto either the molecules that make up the cell membranes or intercellularmilieu, or changes to the mechanical structural integrity of the stratumcorneum and/or hair follicles can result in reduced barrier function. Itis believed that irradiation of the skin with radiant energy produced bythe Er:YAG laser causes measurable changes in the thermal properties, asevidenced by changes in the Differential Scanning Calorimeter (DSCspectra as well as the Fourier Transform Infrared (FTIR) spectra ofstratum corneum. Changes in DSC and FTIR spectra occur as a consequenceof changes in molecules or macromolecular structure, or the environmentaround these molecules or structures. Without wishing to be bound to anyparticular theory, we can tentatively attribute these observations tochanges in lipids, water and protein molecules in the stratum corneumcaused by irradiation of molecules with electromagnetic radiation, bothby directly changing molecules as well as by the production of heat andpressure waves which can also change molecules.

[0016] Both perforation and alteration change the permeabilityparameters of the skin in a manner which allows for increased passage ofbody fluids or pharmaceuticals across the stratum corneum.

[0017] The term “lyse” is used herein to indicate the breaking up of theepidermis layer covering a microblister. The energy pulse used toaccomplish this is between the energy required for ablation andsub-ablation.

[0018] Accordingly, one object of the present invention is to provide ameans for perforating or altering the stratum corneum of a patient in amanner that does not result in bleeding. For example, the perforation oralteration created at the target tissue is accomplished by applying alaser beam that penetrates through the stratum corneum layer or both thestratum corneum layer and the epidermis, thereby reducing or eliminatingthe barrier function of the stratum corneum. This procedure allows forthe subsequent removal of fluids, specifically interstitial fluid,through the skin.

[0019] Another object of this invention is to draw interstitial fluidthrough the perforation or alteration site (or allowing the interstitialto propagate on its own to the surface of the skin). The interstitialfluid can then be collected.

[0020] In a preferred embodiment, by selection of appropriatewavelength, energy fluence, pulse temporal width and irradiation spotsize, the skin tissue is perforated deep into the epidermis. Afterperforation, interstitial fluid is collected into an awaiting container.

[0021] In a further preferred embodiment, by selection of appropriatewavelength, energy fluence, pulse temporal width and irradiation spotsize, just the stratum corneum is perforated or altered and theinterstitial fluid is then allowed to propagate to surface. The fluid isthen collected into a container unit for testing, or the fluid is lefton the skin surface for subsequent testing.

[0022] In an additional preferred embodiment, before perforation oralteration by the laser device, a blister, preferably a microblister, iscreated at the surface of the skin by subjecting the skin tosub-atmospheric pressure. This vacuum can be created by a separatedevice, or the vacuum system can be part of the laser perforatorcontainer unit. After the skin has been subjected to sub-atmosphericpressure (a pressure of slightly less than 1 atmosphere), a microblisteris formed, whereby the epidermis is separated from the dermis.Interstitial fluid collects in this pocket and the laser perforator isthen used to lyse the blister. After lysing, the interstitial fluid thatformed inside the blister is collected into a container.

[0023] To further the speed in the collection of interstitial fluid, orto increase the delivery of pharmaceuticals into the body, pressuregradients in the tissue can be created. In this embodiment, pressuregradients are created using short rapid pulses of radiant energy on thetissue. This pressure gradient can be used to force substances, such asinterstitial fluid, out of the body, or to transfer a substance into thebody, through a perforation or alteration site. In another embodiment ofthis invention, pressure waves, plasma, and cavitation bubbles arecreated in or above the stratum corneum to increase the permeation ofthe compounds (e.g., pharmaceuticals) or fluid, gas or other biomoleculeremoval. This method may simply overcome the barrier function of intactstratum corneum without significant alteration or may be used toincrease permeation or collection in ablated or altered stratum corneum.Additionally, to increase diffusion, plasma can be produced byirradiating the surface of the target tissue, or material on the targettissue, with a pulse or pulses of electromagnetic energy from a laser.Prior to treatment, the care giver properly selects the wavelength,energy fluence (energy of the pulse divided by the area irradiated),pulse temporal width and irradiation spot size to create the plasmawhile limiting undesired damage to healthy proximal tissue. Thesetechnique for increasing the diffusion of fluids through the skin is notmeant to limit the scope of this invention, but is merely an embodiment.Other techniques can be used, such as manual compression of the skinsurrounding the perforation or alteration site, or the care giver canrely simply on the reduced barrier function of the perforation oralteration site for fluid to propagate to the skin surface.

[0024] In another embodiment, a typical laser is modified to include acontainer unit. Such a container unit can be added to: (1) increase theefficiency in the collection of fluids; (2) further testing of thecollected sample, (3) apply a vacuum to the skin surface, (4) reduce thenoise created when the laser beam perforates the patient's tissue; and(5) collect the ablated tissue. The optional container unit isalternatively evacuated to expedite the collection of the releasedmaterials, such as the fluids, or to expedite the blistering of thetissue. The container can also be used to collect only ablated tissue.The noise created from the laser beam's interaction with the patient'sskin may cause the patient anxiety. The optional container unit reducesthe noise intensity and therefore alleviates the patient's anxiety andstress. The container unit also minimizes the risk ofcross-contamination and guarantees the sterility of the collectedsample. The placement of the container unit in the use of this inventionis unique in that it covers the tissue being irradiated, at the time ofirradiation by the laser beam, and is therefore able to collect thefluid and/or ablated tissue as the perforation or alteration occurs.

[0025] An additional object of this invention is to allow the taking ofmeasurements of various fluids constituents, such as glucose, collectedthrough the perforation or alteration site. Typical testing techniquesinclude infrared spectrometry, enzymatic analysis, electro-chemicalanalysis and other means. The testing can be incorporated into the laserperforator device or the testing can be completed on the fluid after thecontainer unit has been removed from the device. Additionally, testingcan be completed on the surface of the skin, at the perforation orablation site, after the interstitial fluid has propagated through thetarget tissue.

[0026] An additional object of this invention is to administerpharmaceuticals after measurement of the interstitial fluid. Theappropriate drug dose can be delivered manually or automatically. Drugdelivery can be triggered in combination with the monitoring of thedesired analyte. For example, glucose measurements can be used totrigger the administration of insulin in diabetics.

[0027] A further object of this invention is to allow drugs to beadministered continually on an outpatient basis over long periods oftime. The speed and/or efficiency of drug delivery is thereby enhancedfor drugs which were either slow or unable to penetrate skin.

[0028] A further object of this invention is to avoid the use of sharps.The absence of a contaminated sharp will eliminate the risk ofaccidental injury and its attendant risks to health care workers,patients, and others that may come into contact with the sharp. Theabsence of a sharp in turn obviates the need for disposal ofbiologically hazardous waste. Thus, the present invention provides anecologically sound method for removing body fluids or administeringpharmaceuticals.

[0029] A typical laser used for this invention requires no specialskills to use (for example, the TRANSMEDICA™ Er:YAG laser). It can besmall, lightweight and can be used with regular or rechargeablebatteries. The greater the laser's portability and ease of use, thegreater the utility of this invention in a variety of settings, such asa hospital room, clinic, or home.

[0030] Safety features can be incorporated into the laser that requirethat no special safety eyewear be worn by the operator of the laser, thepatient, or anyone else in the vicinity of the laser when it is beingused.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention may be better understood and its advantagesappreciated by those skilled in the art by referring to the accompanyingdrawings wherein:

[0032]FIG. 1 shows a laser with its power source, high voltagepulse-forming network, flashlamp, lasing rod, mirrors, housing andfocusing lens.

[0033]FIG. 2 shows an optional spring-loaded interlock and optionallyheated applicator.

[0034]FIG. 3 shows an alternative means of exciting a laser rod using adiode laser.

[0035]FIG. 4 shows an alternative focusing mechanism.

[0036]FIGS. 5A & 5B show optional beam splatters for creating multiplesimultaneous irradiation.

[0037]FIG. 8 shows an optional container unit for collecting fluids,ablated tissue, and/or other matter released from the site ofirradiation, and for reducing noise resulting from the interactionbetween the laser and the patient's tissue.

[0038]FIG. 9 shows a plug and plug perforation center.

[0039]FIG. 10 shows an optional container unit for collecting ablatedtissue and reducing noise resulting from the interaction between thelaser and the patient's tissue.

[0040]FIG. 11 shows a roll-on device for the delivery ofpharmaceuticals.

[0041]FIG. 12 shows an elastomeric mount for a solid state laser crystalelement with optional mirrored surfaces applied to each end of theelement.

[0042]FIG. 13 shows an example of a crystal rod with matte finish aroundthe full circumference of the entire rod.

[0043]FIG. 14 shows an example of a crystal rod with matte finish aroundthe full circumference of two-thirds of the rod.

[0044]FIG. 15 shows an example of a crystal rod with matte stripes alongits longitudinal axis.

[0045]FIG. 16 shows a cross-section of a crystal laser rod elementsurrounded by a material having an index of refraction greater than theindex of refraction of the rod.

[0046] FIGS. 17A-17G show various examples of a container unit.

[0047]FIG. 18 shows an atomizer for the delivery of pharmaceuticals.

[0048]FIG. 19 shows examples of a container unit in use with a laser.

[0049]FIG. 20 shows an example of a lens with a mask.

[0050]FIG. 21 is a chart showing a study using corticosterone whichshowed enhanced permeation through skin irradiated at an energies of 77mJ and 117 mJ.

[0051]FIG. 22 shows the decrease in the impedance of skin using variouslaser pulse energies.

[0052] FIGS. 23-24 show in a permeation study of tritiated water (3H₂O)involving lased human skin at energies from 50 mJ (1.6 J/cm²) to 1250 mJ(40 J/cm²).

[0053]FIG. 25 shows histological sections of human skin irradiated atenergies of 50 mJ and 80 mJ.

[0054]FIG. 26 is a chart of a study using DNA showing enhancedpermeation through skin irradiated at an energy of 150 mJ and 300 mJ.

[0055]FIG. 27 shows laser pulse energy (J) versus water loss throughhuman skin in vivo.

[0056]FIG. 28 is a chart showing a DSC scan of normally hydrated (66%)human stratum corneum, and a scan of Er:YAG laser irradiated stratumcorneum using a subablative pulse energy of 60 mJ.

[0057] FIGS. 29-31 are charts showing the heat of transition (μJ),center of the transition (° C.) and the full-width at half-maximum ofthe transition (° C.) of three peaks in the DSC spectra of stratumcorneum treated different ways.

[0058] FIGS. 32-33 are charts of FTIR spectra of control and lasedstratum corneum.

[0059]FIG. 34 shows Amide I band position (cm⁻¹) as a function ofstratum corneum treatment.

[0060]FIG. 35 shows CH2 vibration position (cm⁻¹) as a function ofstratum corneum treatment.

[0061]FIG. 36 shows a histological section of rat skin that wasirradiated at 80 mJ.

[0062]FIG. 37 shows a histological section of human skin that wasirradiated at 80 mJ.

[0063]FIG. 38 shows in vivo blanching assay results.

[0064]FIG. 39 shows an optional version of the collection container unitthat is especially useful when the container unit includes a reagent formixing with the sample.

[0065]FIG. 40 shows permeation of insulin through human skin in vitro.

[0066]FIG. 41 shows the creation of pressure waves in tissue convergingto a focal point.

[0067]FIG. 42 shows an example of a beam splitter suitable for makingsimultaneous irradiation sites.

[0068]FIG. 43 shows one possible pattern of perforation or alterationsites using a beam splitter.

[0069]FIG. 44 shows a pressure gradient created in the stratum corneum.

[0070]FIG. 45 is a schematic of modulating the pulse repetitionfrequency of radiant energy from high (4 GHz) to low (4 MHz).

[0071]FIG. 46 shows a propagating pressure wave created in an absorbingmaterial located on the skin.

[0072]FIG. 47 shows a propagating pressure wave created at the skinsurface with a transparent, or partially transparent, optic located onthe skin.

[0073]FIG. 48 shows a propagating pressure wave created in an absorbingmaterial on the applied pharmaceutical.

[0074]FIG. 49 shows a propagating pressure wave created in the appliedpharmaceutical.

DETAILED DESCRIPTION

[0075] This invention provides a method for perforating or altering skinfor the sampling and measurement of body fluids. The invention utilizesa laser beam, specifically focused, and lasing at an appropriatewavelength, to create small perforations or alterations in the skin of apatient. In a preferred embodiment, the laser beam has a wavelengthbetween 0.2 and 10 microns. More preferably, the wavelength is betweenabout 1.5 and 3.0 microns. Most preferably the wavelength is about 2.94microns. In one embodiment, the laser beam is focused with a lens toproduce an irradiation spot on the skin through the epidermis of theskin. In an additional embodiment, the laser beam is focused to createan irradiation spot only through the stratum corneum of the skin.

[0076] The caregiver may consider several factors in defining the laserbeam, including wavelength, energy fluence, pulse temporal width andirradiation spot-size. In a preferred embodiment, the energy fluence isin the range of 0.03-100,000 J/cm². More preferably, the energy fluenceis in the range of 0.03-9.6 J/cm². The beam wavelength is dependent inpart on the laser material, such as Er:YAG. The pulse temporal width isa consequence of the pulse width produced by, for example, a bank ofcapacitors, the flashlamp, and the laser rod material. The pulse widthis optimally between 1 fs (femtosecond) and 1,000 μs.

[0077] According to the method of the present invention the perforationor alteration produced by the laser need not be produced with a singlepulse from the laser. In a preferred embodiment the caregiver produces aperforation or alteration through the stratum corneum by using multiplelaser pulses, each of which perforates or alters only a fraction of thetarget tissue thickness.

[0078] To this end, one can roughly estimate the energy required toperforate or alter the stratum corneum with multiple pulses by takingthe energy in a single pulse, and dividing by the number of pulsesdesirable. For example, if a spot of a particular size requires 1 J ofenergy to produce a perforation or alteration through the entire stratumcorneum, then one can produce qualitatively similar perforation oralteration using ten pulses, each having {fraction (1/10)}th the energy.Because it is desirable that the patient not move the target tissueduring the irradiation (human reaction times are on the order of 100 msor so), and that the heat produced during each pulse not significantlydiffuse, in a preferred embodiment the pulse repetition rate from thelaser should be such that complete perforation is produced in a time ofless than 100 ms. Alternatively, the orientation of the target tissueand the laser can be mechanically fixed so that changes in the targetlocation do not occur during the longer irradiation time.

[0079] To penetrate the skin in a manner which does not induce much ifany blood flow, skin is perforated or altered through the outer surface,such as the stratum corneum layer, but not as deep as the capillarylayer. The laser beam is focussed precisely on the skin, creating a beamdiameter at the skin in the range of approximately 0.5 microns-5.0 cm.Optionally, the spot can be slit-shaped, with a width of about 0.05-0.5mm and a length of up to 2.5 mm. The width can be of any size, beingcontrolled by the anatomy of the area irradiated and the desiredpermeation rate of the fluid to be removed or the pharmaceutical to beapplied. The focal length of the focusing lens can be of any length, butin one embodiment it is 30 mm.

[0080] By modifying wavelength, pulse length, energy fluence (which is afunction of the laser energy output (in Joules) and size of the beam atthe focal point (cm²)), and irradiation spot size, it is possible tovary the effect on the stratum corneum between ablation (perforation)and non-ablation or partial alteration (alteration). Both ablation andnon-ablative alteration of the stratum corneum result in enhancedpermeation of body fluids or subsequently applied pharmaceuticals.

[0081] For example, by reducing the pulse energy while holding othervariables constant, it is possible to change between ablative andnon-ablative tissue-effect. Using the TRANSMEDICA™ Er:YAG laser, whichhas a pulse length of about 300 μs, with a single pulse or radiantenergy and irradiating a 2 mm spot on the skin, a pulse energy aboveapproximately 100 mJ causes partial or complete ablation, while anypulse energy below approximately 100 mJ causes partial ablation ornon-ablative alteration to the stratum corneum. Optionally, by usingmultiple pulses, the threshold pulse energy required to enhancepermeation of body fluids or for pharmaceutical delivery is reduced by afactor approximately equal to the number of pulses.

[0082] Alternatively, by reducing the spot size while holding othervariables constant, it is also possible to change between ablative andnon-ablative tissue-effect. For example, halving the spot area willresult in halving the energy required to produce the same effect.Irradiations down to 0.5 microns can be obtained, for example, bycoupling the radiant output of the laser into the objective lens of amicroscope objective. (e.g., as available from Nikon, Inc., Melville,N.Y.). In such a case, it is possible to focus the beam down to spots onthe order of the limit of resolution of the microscope, which is perhapson the order of about 0.5 microns. In fact, if the beam profile isGaussian, the size of the affected irradiated area can be less than themeasured beam size and can exceed the imaging resolution of themicroscope. To non-ablatively alter tissue in this case, it would besuitable to use a 3.2 J/cm² energy fluence, which for a half-micron spotsize, would require a pulse energy of about 5 nJ. This low a pulseenergy is readily available from diode lasers, and can also be obtainedfrom, for example, the Er:YAG laser by attenuating the beam by anabsorbing filter, such as glass.

[0083] Optionally, by changing the wavelength of radiant energy whileholding the other variables constant, it is possible to change betweenan ablative and non-ablative tissue-effect. For example, using Ho:YAG(holmium:YAG; 2.127 microns) in place of the Er:YAG (erbium:YAG; 2.94microns) laser, would result in less absorption of energy by the tissue,creating less of a perforation or alteration.

[0084] Picosecond and femtosecond pulses produced by lasers can also beused to produce alteration or ablation in skin. This can be accomplishedwith modulated diode or related microchip lasers, which deliver singlepulses with temporal widths in the 1 femtosecond to 1 ms range. (See D.Stern et al., “Corneal Ablation by Nanosecond, Picosecond, andFemtosecond Lasers at 532 and 625 nm,” Corneal Laser Ablation, vol. 107,pp. 587-592 (1989), incorporated herein by reference, which disclosesthe use of pulse lengths down to 1 femtosecond).

[0085] According to another object of this invention, after perforationor alteration of the target tissue, interstitial fluid is collected forsubsequent measurement. To further collection of the fluid, differentperforation or alteration depths can be created. In a preferredembodiment, the laser device perforates through the epidermis, allowingthe interstitial fluid to propagate to the surface of the skin. In anadditional preferred embodiment, perforation or alteration through thestratum corneum is completed, allowing the interstitial fluid topropagate to the surface of the skin, albeit more slowly.

[0086] Blistering to Enhance Collection of Interstitial Fluid

[0087] In a further embodiment, the laser perforator device is used incombination with sub-atmospheric pressure to obtain samples ofinterstitial fluid. By purposely applying a vacuum to the surface of theskin, it is possible to gently and reversibly separate the epidermisfrom the underlying dermis, thus creating a microblister in whichinterstitial fluid can collect.

[0088] The epidermis and dermis are interlocked by ridges and root likecytoplasmic microprocesses of basal cells that extend into thecorresponding indentations of the dermis. This junction is furtherenforced by desmosomes which anchor the basal cells on the basal lamina,which is itself attached to the dermis by anchoring filaments andfibrils. In some cases, the hydrodynamic pressure of the plasma releasedby the superficial dermal blood vessels can lead to a lifting of thebasal cells from the basal lamina thus leading to a (junctional)blister. Such a blister can be induced by suction, mild heat, certaincompounds or liquid nitrogen. See Dermatology in General Medicine, 3ded., T B Fitzpatrick, A Z Eisen, K. Wolff, I M Freedberg, and K FAusten, McGraw—Hill:NY (1987), incorporated herein by reference.

[0089] Low and Van der Leun (“Suction Blister Device for Separation ofViable Epidermis from Dermis”, vol. 50, No. 2, pp. 308-314, Journal ofInvestigative Dermatology, 1968) describe the use of suction blisters,created in lower abdominal skin with reduced vacuum, for the purpose ofobtaining interstitial fluid. They report that t=a/p, where a is aconstant (9×10⁸ dyne/cm²/sec) and p is the suction pressure. Thus, forexample, a suction pressure of 200 mm Hg (760 mm Hg or 1.013×10⁶dyne/cm² is atmospheric pressure) will produce a blister in about 60minutes. Van der Leun et al., (vol. 62, pp. 42-46, Journal ofInvestigative Dermatology, 1974), make the point that if skintemperature is raised (from 24° C. to 34° C., for example), the time tothe onset of the blister (for pressure of 410 mm Hg) is reduced from 30to 7 minutes.

[0090] One embodiment of the present invention is to form a microblisterby using negative pressure (slightly less than 1 atmosphere) applied toa small area on the skin. Subsequent lysing of the blister with thelaser device produces a pathway through which the interstitial fluid canbe collected. The vacuum acts to enhance the volume of interstitialfluid.

[0091] In another embodiment of the present invention, the vacuum meansfor drawing a microblister is incorporated into the lasing device. In anadditional embodiment, the vacuum means is performed by an alternativedevice and the laser is then used to lyse the formed microblister.

[0092] In a further embodiment of the present invention, the vacuum isapplied after ablation or alteration of the tissue, thereby propagatingfluid through the lased site by negative pressure.

[0093] Pressure Wave to Enhance the Permeability of the Stratum Corneumor Other Membranes

[0094] In another embodiment of the present invention, a pressuregradient is created at the ablated or altered site to force substancesthrough the skin. This technique can be used for the introduction ofcompounds including pharmaceuticals into the body or to remove fluids,gases or biomolecules from the body.

[0095] When laser radiant energy is absorbed by tissue, expansion (dueto heating) and/or physical movement of tissue (due to heating ornon-thermal effects such as spallation) takes place. These phenomenalead to production of propagating pressure waves, which can havefrequencies in the acoustic (20 Hz to 20,000 Hz) or ultrasonic (>20,000Hz) region of the pressure wave spectrum. For example, Flock et al.(Proc SPIE Vol. 2395, pp. 170-176, 1995) show that when a 20 ns pulsefrom a Q-switched frequency-doubled Nd:YAG laser is impacted on blood,propagating transient high pressure waves form. These pressure waves canbe spectrally decomposed to show that they consist of a spectrum offrequencies, from about 0 to greater than 4 MHz. The high-pressuregradient associated with these kinds of compressional-type pressurewaves can be transformed into tension-type or stress waves which can“tear” tissue apart in a process referred to as “spallation”.

[0096] The absorption of propagating pressure waves by tissue is afunction of the tissue type and frequency of wave. Furthermore, thespeed of these pressure waves in non-bone tissue is approximately1400-1600 m/sec. Using these observations, a pressure gradient in tissuecan be created, directed either into the body or out of the body, usingpulsed laser radiant energy. To efficiently create pressure waves with apulsed laser, the pulse duration needs to be less than the time it takesfor the created heat to diffuse out of the region of interest. Theeffect is qualitatively equivalent to the effects of ultrasound ontissue. The attenuation coefficient for sound propagation in tissueincreases approximately linearly with frequency (see, for example, J.Havlice and J. Taenzer, “Medical Ultrasound Imaging: An Overview ofPrinciples and Instrumentation”, Proc. IEEE 67, 620-641, 1979), and isapproximately 1 dB/cm/MHz (note that a 20 decibel (dB) intensitydifference is equivalent to a factor of 10 in relative intensity). Thethickness of the stratum corneum is about 25 microns and the epidermisis about 200 microns. Thus, the frequency that is attenuated by 10 dBwhen propagating through the stratum corneum is 10 dB/(1dB/cm/MHz*0.0025 cm), or 4 GHz. Similarly, as strongly absorbed radiantenergy produced by a pulsed laser (say pulsed at 4 GHz) will producepropagating pressure waves of a similar frequency as the pulserepetition rate, it is possible to selectively increase the pressure inthe stratum corneum or upper layers of skin as compared to the lowerlayers, thus enhancing the diffusive properties of topically applieddrug (see, e.g., FIG. 44). A transparent, or nearly transparent, optic172, as shown in FIG. 47, can be placed on the surface of the skin tocontain the backward inertia of the propagating pressure wave or ablatedstratum corneum.

[0097] In an additional embodiment, as shown in FIG. 45, by modulatingthe pulse repetition frequency of the radiant energy from high to low,it is possible to create transient pressure fields that can be designedto be beneficial for enhancing the diffusive properties of a topicallyapplied pharmaceutical.

[0098] The high-frequency propagating pressure waves can also beproduced from a single laser pulse. When tissue absorbs a brief pulse oflaser irradiation, pressure waves with a spectrum of frequencies result.Some of these frequencies will propagate into lower layers in the skin,thus it may be possible to set up a reverse pressure gradient (morepressure below and less superficially) in order to enhance the diffusionof biomolecules out of the body effectively “pumping” them through theskin.

[0099] Acoustic waves and/or spallation are believed to occur during theuse of the TRANSMEDICA™ Er:YAG laser in ablation of stratum corneum fordrug delivery or perforation, since the 2.94 micron radiant energy isabsorbed in about 1 micron of tissue, yet the tissue ablation can extendmuch deeper.

[0100] A continuous-wave laser can also be used to create pressurewaves. A continuous-wave laser beam modulated at 5-30 MHz can produce0.01-5 W/cm² pressure intensities in tissue due to expansion andcompression of sequentially heated tissue (for example, a Q-switchedEr:YAG laser (40 ns pulse) at 10 mJ and focussed to a spot size of 0.05cm, with a pulse repetition rate of 5-30 MHz, would produce in stratumcorneum a stress of about 3750 bars, or 0.025 W/cm²). It takes a fewhundred bars to cause transient permeability of cells. With this laserit requires about 0.01 W/cm² of continuous pressure wave energy toprovide effective permeation of skin.

[0101] In an additional embodiment, pressure waves are induced on thetopically applied pharmaceutical. The propagation of the wave towardsthe skin will carry some of the pharmaceutical with it (see, e.g., FIG.49).

[0102] In a further embodiment, pressure waves are induced on anabsorbing material 170 placed over the topically applied pharmaceutical(see, e.g., FIG. 48). Preferably this material is a thin film of water,however, it can be created in any liquid, solid or gas located over thetopically applied pharmaceutical. The propagation of the wave towardsthe skin will carry some of the pharmaceutical with it. Additionally,pressure waves can be induced on an absorbing material 170 (preferably athin film of water, however, it can be created in any liquid, solid orgas) placed over the target tissue. (see, e.g., FIG. 46). Thepropagation of the wave towards the skin will increase the permeabilityof the stratum corneum. Subsequent to the formation of these pressurewaves, the desired pharmaceutical can be applied.

[0103] In another embodiment, pressure gradients can be used to removefluids, gases or other biomolecules from the body. This can beaccomplished by focusing a beam of radiant energy down to a small volumeat some point within the tissue. The resulting heating leads to pressurewave intensities (which are proportional to the degree of heating) thatwill be greater near the focal point of the radiant energy, and lessnear the surface. The consequence of this is a pressure gradientdirected outwards thus enhancing the removal of fluids, gases or otherbiomolecules. Alternatively, propagating pressure waves created at thesurface of the skin can be focused to a point within the tissue. Thiscan be done, for example, by using a pulsed laser to irradiate a solidobject 174 above the skin, which by virtue of its shape, inducespressure waves in the tissue which converges to the focal point (see,e.g., FIG. 41). Again, the consequence of this is a pressure gradientdirected outwards thus enhancing the removal of fluids, gases or otherbiomolecules.

[0104] The pressure waves described can be created after perforation oralteration of the stratum corneum has taken place. Alternatively,pressure waves can be used as the sole means to increase the diffusiveproperties of compounds trough the skin or the removal of fluids, gasesor other biomolecules.

[0105] Creation of Cavitation Bubbles to Increase Stratum CorneumPermeability

[0106] Cavitation bubbles, produced subsequent to the target tissuesperforation or alteration, can be used to enhance the diffusiveproperties of a topically applied drug. While production of cavitationbubbles within the tissue is known (See, for example, R. Ensenaliev etal., “Effect of Tensile Amplitude and Temporal Characteristics onThreshold of Cavitation-Driven Ablation,” Proc. SPIE vol. 2681, pp326-333, (1996)), for the present invention, cavitation bubbles areproduced in a material on or over the surface of the skin so that theypropagate downwards (as they do because of conservation of momentum) andimpact on the stratum corneum, thereby reducing the barrier function ofthe skin. The cavitation bubbles can be created in an absorbing material170 located on or over the skin.

[0107] Cavitation has been seen to occur in water at −8 to −100 bars,(Jacques et al. Proc. SPIE vol. 1546, p. 284 (1992)). Thus, using aQ-switched Er:YAG laser (40 ns pulse) at 10 mJ and focussed to a spotsize of 0.05 cm in a thin film of water on the skin, with a pulserepetition rate of 5-30 MHz, a stress of about 3750 bars, or 0.025W/cm², is produced. This should generate the production of cavitationbubbles, which, when they contact the skin will cause mechanical and/orthermal damage thereby enhancing stratum corneum permeability.

[0108] In a preferred embodiment, the cavitation bubbles are produced ina thin film of water placed on or over the skin, however, any liquid orsolid material can be used. Subsequent to production of the cavitationbubbles a pharmaceutical is applied to the affected tissue.

[0109] In an additional embodiment, cavitation bubbles are produced inthe administered pharmaceutical subsequent to its application on theskin. Cavitation bubbles can also be produced in the stratum corneumitself before pharmaceutical application.

[0110] In a further embodiment, the target tissue is not perforated oraltered before the production of cavitation bubbles, the cavitationbubbles' impact on the stratum corneum being the only method used toincrease stratum corneum permeability.

[0111] Plasma Ablation to Increase Stratum Corneum Permeability

[0112] Plasma is a collection of ionized atoms and free electrons. Ittakes an extremely strong electric field or extremely high temperatureto ionize atoms, but at the focus of an intense pulsed laser beam(>approx. 10⁸-10¹⁰ W/cm²), such electric fields can result. Above thisenergy fluence rate, high enough temperatures can result. What one seeswhen plasma is formed is a transient bright white cloud (which resultsfrom electrons recombining with atoms resulting in light emission atmany different wavelengths which combine to appear to the eye as white).A loud cracking is usually heard when plasma is formed as a result ofsupersonic shock waves propagating out of the heated (>1000K) volumethat has high pressures (perhaps >1000 atmospheres). Since plasma is acollection of hot energetic atoms and electrons, it can be used totransfer energy to other matter, such as skin. See Walsh J T,“Optical-Thermal Response of Laser-Irradiated Tissue,” Chapter 25, pp.865-902 (Plenum Press, NY 1995), incorporated by reference herein as iffully set forth in its entirety. For example, U.S. Pat. No. 5,586,981,issued to Hu, discloses the use of plasma to treat cutaneous vascular orpigmented lesions. The wavelength of the laser in Hu '981 is chosen suchthat the laser beam passes through the epidermal and dermal layers ofskin and the plasma is created within the lesion, localizing thedisruption to the targeted lesion.

[0113] A plasma can also be used to facilitate diffusion through thestratum corneum. In one embodiment of the present invention, plasma isproduced above the surface of the skin whereupon a portion of the plasmacloud will propagate outwards (and downwards) to the skin whereupon,ablation or tissue alteration will occur. Plasma can be created in aliquid, solid or gas that is placed on or over the skin, into which thelaser beam is focussed. If the plasma is created in a material with anacoustic impedance similar to tissue (say, a fluid), then the resultingpressure waves would tend to transfer most of their energy to the skin.The plasma “pressure wave” behaves similarly to propagating pressurewaves. This is due to the fact that the acoustic impedance mismatch atthe upper surface between air and solid/liquid material is high, and,furthermore, plasma, like ultrasonic energy propagates poorly inlow-density (i.e. air) media.

[0114] In another embodiment, plasma is produced within the stratumcorneum layer. Because the energy fluence rate needed to produce theplasma is as high as approximately 108 W/cm2, selection of a wavelengthwith radiant energy that is strongly absorbed in tissue is not animportant concern.

[0115] Important benefits in these embodiments are that (1) the opticalabsorption of material to produce plasma is not an importantconsideration, although the energy fluence rate required to produce theplasma is less when the irradiated material strongly absorbs theincident radiant energy, and (2) there are relatively inexpensivediode-pumped Q-switched solid state lasers that can produce therequisite radiant energy (such as are available from Cutting EdgeOptronics, Inc., St, Louis, Mo.).

[0116] To obtain a peak energy fluence rate greater than orapproximately equal to the plasma creation threshold of 10⁸ W/cm², usinga pulse length of 300 μs (e.g. for the TRANSMEDICA™ Er:YAG laser, 1 Jfor 300 μs), the pulse power is 3333 W, and the spot size needs to be0.0065 mm. Alternatively, a small diode-pumped Q-switched laser can beused. Such lasers have pulse widths on the order of 10 ns, and, as such,the requisite spot size for producing plasma could be much larger.

[0117] Continuous-Wave (CW) Laser Scanning

[0118] It is possible, under machine and microprocessor control, to scana laser beam (either continuous-wave or pulsed) over the target tissue,and to minimize or eliminate thermal damage to the epidermis or adjacentanatomical structures.

[0119] For example, a scanner (made up of electro-optical or mechanicalcomponents) can be fashioned to continually move the laser beam over auser-defined area. This area can be of arbitrary size and shape. Thepath for the scan could be spiral or raster. If the laser is pulsed, ormodulated, then it would be possible to do a discrete random patternwhere the scanning optics/mechanics directs the beam to a site on theskin, the laser lases, and then the scanning optics/mechanics directsthe beam to a different site (preferable not adjacent to the first spotso that the skin has time to cool before an adjacent spot is heated up).

[0120] This scanning technique has been used before with copper-vaporlasers (in treating port-wine stains) and is in use with CO₂ lasers forthe purpose of facial resurfacing. In the case of the former, thesubepidermal blood vessels are targeted, while in the latter, about 100microns of tissue is vaporized and melted with each laser pass.

[0121] Interstitial Fluid Testing

[0122] Interstitial fluid contains concentrations of analytes thatcorrelate with the concentration of analytes in other body fluids, suchas blood. As such, the interstitial fluid analyte concentration can betested to give an accurate measurement of analytes present in other bodyfluids.

[0123] One embodiment of the present invention is to perform testing ona number of analytes in the collected interstitial fluid sample toaccurately measure levels of the analytes in other body fluids. Forexample, Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺, Cl⁻, HCO₃ ⁻, HHCO₃, phosphates, S₄ ⁻⁻,glucose, amino-acid, cholesterol, phospholipids, neutral fat, PO₂ ⁻⁻,pH, organic acids and/or proteins are components of interstitial fluidand can be monitored. See N. Tietz, Textbook of Clinical Chemistry, W.B. Saunders Co., Philadelphia (1986), incorporated herein by reference.Interstitial fluid is, in many ways, filtered plasma, and has a similarconstitution as plasma, except that some of the large proteins arefiltered out by walls of the blood vessel. As such, components that canbe assayed in serum can be assayed in interstitial fluid and suchinterstitial fluid components may be directly correlated to serumcomponents. In one embodiment of this invention glucose in interstitialfluid is tested to monitor and treat blood sugar levels in diabetics.

[0124] Following the collection of interstitial fluid, as detailedabove, the sample is tested for the specific analyte of interest, suchas glucose. For glucose, testing can be done by infrared measurements,enzymatic analysis, or other testing protocols. Sodium and potassium areusually detected with ion-specific electrodes which allow a particularion to penetrate an electrode, whereupon a current proportional to theion concentration is produced and detected (analogous to a pH meter).Proteins are detected in various ways, for example, enzyme linkedimmunoassay (ELISA), gel electrophoresis, ultracentrifugation,radioimmunoassays, and fluorescence. These methodologies are discussedin N. Tietz, Textbook of Clinical Chemistry, W. B. Saunders Co.,Philadelphia (1986).

[0125] There are a variety of substances that can be detected ininterstitial fluid that are not normally present in apparently healthyindividuals. Many of these substances are detected by colorimetry (afterreacting the analyte with a test chemical), flame photometry, atomicabsorption spectrometry, gas or mass spectrometry, and high-pressureliquid chromatography. For example, ethanol is detectable by reaction ofthe analyte with alcohol dehydrogenase, followed by colorimetry. Thesetesting examples are not meant to limit the scope of the invention, butare merely embodiments.

[0126] In one embodiment the testing is completed as part of the laserperforation or alteration process. Using infrared radiation, forexample, testing can be conducted in the container unit attached to thelaser device. A section of the container unit, or the entire unit, isoptionally constructed of a material that passes a predetermined lightwavelength (e.g., for glucose, nylon, polyethylene or polyamide, whichare partially transparent to infrared energy at 1040 nm, a wavelengthabsorbed by glucose, can be used). By sending light of known intensitythrough the container unit, as well as a reference beam sent through aportion of the container with no interstitial fluid, the absorption ofthe sample can be determined. A photosensitive diode, or other lightdetector is placed on the opposite side of the container unit from thelight source. Absorption is determined by signals sent by the lightdetector. Based on absorption, the concentration of the analyte can thenbe determined. Specific techniques for conducting this type of infrared,or other spectrum analysis, can be found in U.S. Pat. No. 5,582,184,issued to Erickson et al. and D. A. Christensen, in Vol. 1648Proceedings of Fiber Optic, Medical and Fluorescent Sensors andApplications, pp. 223-26 (1992), both incorporated herein by reference.

[0127] In a further embodiment of the present invention, following thecollection of the interstitial fluid, the desired analyte is subjectedto enzymatic means. For example, to determine glucose concentration,glucose can be oxidized using glucose oxidase. This createsgluconolactone and hydrogen peroxide. In the presence of colorlesschromogen, the hydrogen peroxide is converted to water and a coloredproduct. Because the intensity of the colored product is proportional tothe amount of glucose, conventional absorbance or reflectance methodscan be used to determine concentration. By calibrating the color toglucose concentration, the concentration of glucose can thereafter bevisually approximated. Specific techniques for conducting this type ofanalysis can found in U.S. Pat. No. 5,458,140, issued to Eppstein etal., incorporated herein by reference.

[0128] In an additional embodiment of the present invention, the testinganalysis can be electronically processed and fed to a digital readout,or other suitable means, on the lasing device.

[0129] In another embodiment of the present invention, the interstitialfluid is removed from the container unit, or the fluid is collected in aseparate device. After collection, the above described testing methodscan be conducted using separate equipment or by sending the sample to atesting laboratory.

[0130] In a further embodiment, after perforation or alteration, testingis completed on the tissue using separate methods or devices. Forexample, the 1994 monitoring technique described by N. Ito et al.(“Development of a Transcutaneous Blood-Constituent Monitoring MethodUsing a Suction Effusion Fluid Collection Technique and an Ion-SensitiveField-Effect Transistor Glucose Sensor”, vol. 32, No. 2, pp. 242-246,Medical & Biological Engineering & Computing, 1994), incorporated hereinby reference, can be conducted at the site of perforation or alteration.

[0131] Delivery of a Pharmaceutical

[0132] A laser can be used to perforate or alter the skin through theouter surface, such as the stratum corneum layer, but not as deep as thecapillary layer, to allow pharmaceuticals to be topically administered.Pharmaceuticals must penetrate the stratum corneum layer in order to beeffective. Presently, compounds acting as drug carriers are used tofacilitate the transdermal diffusion of some drugs. These carrierssometimes change the behavior of the drug, or are themselves toxic.

[0133] With the other parameters set, the intensity of the laser pumpsource will determine the intensity of the laser pulse, which will inturn determine the depth of the resultant perforation or alteration.Therefore, various settings on the laser can be adjusted to allowperforation or alteration of different thickness' of stratum corneum.

[0134] Optionally, a beam-dump can be positioned in such a way as not toimpede the use of the laser for perforation or alteration ofextremities. The beam-dump will absorb any stray electromagneticradiation from the beam that is not absorbed by the tissue, thus,preventing any scattered rays from causing damage. The beam-dump can bedesigned so as to be easily removed for situations when the presence ofthe beam-dump would impede the placement of a body part on theapplicator.

[0135] This method of delivering a pharmaceutical creates a very smallzone in which tissue is irradiated, and only an extremely small zone ofthermal necrosis. A practical round irradiation site can range from0.1-5.0 cm in diameter, while a slit shaped hole can range fromapproximately 0.05-0.5 mm in width and up to approximately 2.5 mm inlength, although other slit sizes and lengths can be used. As a result,healing is quicker than or as quick as the healing after a skin puncturewith a sharp implement. After irradiation, pharmaceuticals can then beapplied directly to the skin or in a pharmaceutically acceptableformulation such as a cream, ointment, lotion or patch.

[0136] Alternatively, the delivery zone can be enlarged by strategiclocation of the irradiation sites and by the use of multiple sites. Thepresent method can be used for transport of a variety ofpharmaceuticals. For example, a region of skin may be anesthetized byfirst scanning the desired area with a pulsing laser such that eachpulse is sufficient to cause perforation or alteration. This can beaccomplished with modulated diode or related microchip lasers, whichdeliver single pulses with temporal widths in the 1 femtosecond to 1 msrange. Anesthetic (e.g., 10% lidocaine) would then be applied over thetreated area to achieve a zone of anesthesia.

[0137] According to one embodiment of the present invention, apharmaceutical is administered immediately after the analyte of interesthas been measured. For example, in the case of glucose, aftermeasurement, a signal can be sent to a drug reservoir to deliver anappropriate amount of insulin. Two embodiments of this inventionincorporate an atomizer (FIG. 18) or a roll-on device (FIG. 11). In thecase of a roll-on device, the laser beam propagates through hole 162incorporated in ball 164 of the roll-on device. In the alternative, theroll-on device can be positioned adjacent to the path of the laser beamthrough the disposable applicator. After measurement, if needed, theroll-on device is rolled over the irradiated site, thereby administeringthe desired pharmaceutical. In the case of an atomizer, thepharmaceutical is administered from a drug reservoir 166 through the useof compressed gas. After measurement of the desired analyte, a cylinder168 containing compressed gas (such as, for example, carbon dioxide) canbe triggered to spray a set amount of pharmaceutical, such as insulin,over the irradiated site.

[0138] In another embodiment of the present invention, an ink jet ormark is used for marking the site of irradiation. The irradiated sitesare often not easily visible to the eye, consequently the health careprovider may not know exactly where to collect the fluid sample or toapply the pharmaceutical. This invention further provides techniques tomark the skin so that the irradiation site is apparent. For example, anink-jet (analogous to those used in ink-jet printers) can be engagedprior to, during or immediately after laser irradiation. Additionally, acircle can be marked around the irradiation site, or a series of linesall pointing inward to the irradiation site can be used. Alternatively,a disposable safety-tip/applicator can be marked on the end (the endthat touches up against the skin of the patient) with a pigment.Engaging the skin against the applicator prior to, during, orimmediately after lasing results in a mark on the skin at the site ofirradiation.

[0139] For certain purposes, it is useful to create multipleperforations or alterations of the skin simultaneously or in rapidsequence. To accomplish this, a beam-splitter or multiply pulsed lasercan optionally be added to the laser or a rapidly pulsing laser, such asa diode or related microchip laser, may be used. Multiple irradiatedsites, created simultaneously or sequentially, would result in anincreased uptake of drugs as compared to a single irradiation site (i.e.an increase in uptake proportional to the total number of ablatedsites). An example of a beam splitter 48 suitable for makingsimultaneous irradiation sites can be found in FIG. 42. Any geometricpattern of spots can be produced on the skin using this technique.Because the diffusion of fluid out of the skin or drugs into skin can beapproximated as symmetric, a beneficial pattern of irradiation spots(such that a uniform local concentration would result over as wide anarea as possible) would be to position each spot equidistant from eachother in a staggered matrix pattern (FIG. 43).

[0140] Alternatively, multiple irradiation sites, or an irradiated areaof arbitrary size and shape, could be produced with use of a scanner.For example, oscillating mirrors which reflect the beam of laser radiantenergy can operate as a scanner.

[0141] For application of the laser device in fluid removal orpharmaceutical delivery, the laser is manipulated in such a way that aportion of the patient's skin is positioned at the site of the laserfocus within the applicator. For perforations or alterations for fluid,gas or other biomolecule removal or pharmaceutical delivery, a region ofthe skin which has less contact with hard objects or with sources ofcontamination is preferred, but not required. Examples are skin on thearm, leg, abdomen or back. Optionally, the skin heating element isactivated at this time in order to reduce the laser energy required foraltering or ablating the stratum corneum.

[0142] Preferably a holder is provided with a hole coincident with thefocal plane of the optical system. Optionally, as shown in FIG. 2, aspring-loaded interlock 36 can be attached to the holder, so that whenthe patient applies a small amount of pressure to the interlock, torecess it to the focal point, a switch is closed and the laser willinitiate a pulse of radiation. In this setup, the focal point of thebeam is not in line with the end of the holder until that end isdepressed. In the extremely unlikely event of an accidental discharge ofthe laser before proper positioning of the tissue at the end of thelaser applicator, the optical arrangement will result in an energyfluence rate that is significantly low, thus causing a negligible effecton unintentional targets.

[0143] The method of this invention may be enhanced by using a laser ofa wavelength that is specifically absorbed by the skin components ofinterest (e.g., water, lipids or protein) which strongly affect thepermeation of the skin tissues. Altering the lipids in stratum corneummay allow enhanced permeation while avoiding the higher energies thatare necessary to affect the proteins and water.

[0144] It would be beneficial to be able to use particular lasers otherthan the Er:YAG for perforation or alteration of tissue. For example,diode lasers emitting radiant energy with a wavelength of 910 nm (0.8microns) are inexpensive, but such wavelength radiation is only poorlyabsorbed by tissue. In a further embodiment of this invention, a dye isadministered to the skin surface, either by application over intactstratum corneum, or by application over an Er:YAG laser treated site (sothe that deep dye penetration can occur), that absorbs such a wavelengthof radiation. For example, indocyanine green (ICG), which is a harmlessdye used in retina angiography and liver clearance studies, absorbsmaximally at 810 nm when in plasma (Stephen Flock and Steven Jacques,“Thermal Damage of Blood Vessels in a Rat Skin-Flap Window Chamber UsingIndocyanine Green and a Pulsed Alexandrite Laser: A Feasibility Study”,Laser Med. Sci. 8, 185-196, (1993)). This dye, when in stratum corneum,is expected to absorb the 810 nm radiant energy from a diode laser (e.g.a GaAlAs laser) thereby raising the temperature of the tissue, andsubsequently leading to ablation or molecular changes resulting inreduced barrier function.

[0145] Alternatively, it is possible to chemically alter the opticalproperties of the skin to enhance subsequent laser radiant energyabsorption without chemicals actually being present at the time of laserirradiation. For example, 5-aminolevulinic acid (5-ALA) is a precursorto porphyrins, which are molecules involved in hemoglobin production andbehavior. Porphyrins are strong absorbers of light. Administration of5-ALA stimulates production of porphyrins in cells, but is itselfconsumed in the process. Subsequently, there will be enhanced absorptionof radiant energy in this tissue at wavelengths where porphyrins absorb(e.g., 400 mm or 630 mm).

[0146] Another way to enhance the absorption of radiant energy instratum corneum without the addition of an exogenous absorbing compoundis to hydrate the stratum corneum by, for example, applying an occlusivebarrier to the skin prior to laser irradiation. In this situation, thewater produced within the body itself continues to diffuse through thestratum corneum and propagate out through pores in the skin, but isprevented from evaporating by the occlusive barrier. Thus, the moistureis available to further saturate the stratum corneum. As the radiantenergy emitted by the Er:YAG laser is strongly absorbed by water, thisprocess would increase the absorption coefficient of the stratumcorneum, and so less energy would be required to induce the alterationsor ablations in the stratum corneum necessary for enhanced topical drugdeliver.

[0147] Additionally, the laser irradiated site eventually heals as aresult of infiltration of keratinocytes and keratin (which takes perhapstwo weeks to complete), or by the diffusion of serum up through theablated sites which form a clot (or eschar) which effectively seals theablated site. For long term fluid collection and measurement, topicaldelivery of drugs, or for multiple sequential administrations of topicaldrugs, it would be beneficial to keep the ablated site open for anextended length of time.

[0148] Thus, in an additional embodiment of this invention, the ablatedor non-ablated site is kept open by keeping the area of irradiationmoist and/or biochemically similar to stratum corneum. This isaccomplished by minimizing contact of air with the ablated site and/orproviding fluid to keep the ablated site moist. The application of apatch (containing, for example, an ointment such as petroleum jelly oran ointment containing hydrocortisone) over the site would help to keepit open. A hydrogel patch would also serve to provide the necessarymoisture. Additionally, cytotoxic drugs such as cisplatin, bleomycin,doxorubicin, and methotrexate, for example, topically applied in lowconcentrations would locally prevent cellular infiltration and woundrepair. Furthermore, application of a vitamin C (ascorbic acid) or otherknown inhibitors of melanin production, following irradiation, wouldhelp to prevent additional skin coloration in the area, followingtreatment.

[0149] Alteration Without Ablation

[0150] There are advantages to the technique of altering and notablating the stratum corneum. In a preferred embodiment, the skin isaltered, not ablated, so that its structural and biochemical makeupallows fluid to diffuse to the skin surface and allows drugs topermeate. The consequence of this embodiment is: (1) the skin afterirradiation still presents a barrier, albeit reduced, to externalfactors such as viruses and chemical toxins; (2) less energy is requiredthan is required to ablate the stratum corneum, thus smaller and cheaperlasers can be used; and (3) less tissue damage occurs, thus resulting inmore rapid and efficient healing.

[0151] Radiant Energy vs Laser Radiant Energy

[0152] The radiant energy emitted by lasers has the properties of beingcoherent, monochromatic, collimated and (typically) intense.Nevertheless, to enhance transdermal drug delivery or fluid, gas orbiomolecule collection, the radiant energy used need not have theseproperties, or alternatively, can have one of all of these properties,but can be produced by a non-laser source.

[0153] For example, the pulsed light output of a pulsed xenon flashlampcan be filtered with an optical filter or other wavelength selectiondevice, and a particular range of wavelengths can be selected out of theradiant energy output. While the incoherent and quasi-monochromaticoutput of such a configuration cannot be focussed down to a small spotas can coherent radiant energy, for the aforementioned purpose that maynot be important as it could be focused down to a spot with a diameteron the order of millimeters. Such light sources can be used in acontinuous wave mode if desirable.

[0154] The infrared output of incandescent lights is significantly morethan their output in the visible, and so such light sources, if suitablyfiltered to eliminate undesirable energy that does not reduce barrierfunction, could be used for this purpose. In another embodiment of theinvention, it would be possible to use an intense incandescent light(such as a halogen lamp), filter it with an optical filter or similardevice, and used the continuous-wave radiant energy output to decreasethe barrier function of stratum corneum without causing ablation. All ofthese sources of radiant energy can be used to produce pulses, orcontinuos-wave radiant energy.

[0155] Laser Device

[0156] The practice of the present invention has been found to beeffectively performed by various types of lasers; for example, theTRANSMEDICA™ Er:YAG laser skin perforator, or the SchwartzElectro-Optical Er:YAG laser. Any pulsed laser producing energy that isstrongly absorbed in tissue may be used in the practice of the presentinvention to produce the same result at a non-ablative wavelength, pulselength, pulse energy, pulse number, and pulse rate. However, laserswhich produce energy that is not strongly absorbed by tissue may also beused, albeit less effectively, in the practice of this invention.Additionally, as described herein, continuous-wave lasers may also beused in the practice of this invention.

[0157]FIGS. 1 and 2 are diagrammatic representations a typical laserthat can be used for this invention. As shown in FIGS. 1 and 2, atypical laser comprises a power connection which can be either astandard electrical supply 10, or optionally a rechargeable battery pack12, optionally with a power interlock switch 14 for safety purposes; ahigh voltage pulse-forming network 16; a laser pump-cavity 18 containinga laser rod 20, preferably Er:YAG; a means for exciting the laser rod,preferably a flashlamp 22 supported within the laser pump-cavity; anoptical resonator comprised of a high reflectance mirror 24 positionedposterior to the laser rod and an output coupling mirror 26 positionedanterior to the laser rod; a transmitting focusing lens 28 positionedbeyond the output coupling mirror; optionally a second focusingcylindrical lens 27 positioned between the output coupling mirror andthe transmitting focusing lens; an applicator 30 for positioning thesubject skin at the focal point of the laser beam, which is optionallyheated for example with a thermoelectric heater 32, attached to thelaser housing 34; an interlock 36 positioned between the applicator andthe power supply; and optionally a beam dump 38 attached to theapplicator with a fingertip access port 40.

[0158] The laser typically draws power from a standard 110 V or 220 V ACpower supply 10 (single phase, 50 or 60 Hz) which is rectified and usedto charge up a bank of capacitors included in the high voltagepulse-forming network 16. Optionally, a rechargeable battery pack 12 canbe used instead. The bank of capacitors establishes a high DC voltageacross a high-output flashlamp 22. Optionally a power interlock 14, suchas a key switch, can be provided which will prevent accidental chargingof the capacitors and thus accidental laser excitation. A furtherinterlock can be added to the laser at the applicator, such as aspring-loaded interlock 36, so that discharge of the capacitors requiresboth interlocks to be enabled.

[0159] With the depression of a switch, a voltage pulse can besuperimposed on the already existing voltage across the flashlamp inorder to cause the flashlamp to conduct, and, as a consequence, initiatethe flash. The light energy from the flashlamp is located in the lasercavity 18 that has a shape such that most of the light energy isefficiently directed to the laser rod 20, which absorbs the lightenergy, and, upon de-excitation, subsequently lases. The laser cavitymirrors of low 26 and high 24 reflectivity, positioned collinearly withthe long-axis of the laser rod, serve to amplify and align the laserbeam.

[0160] Optionally, as shown in FIG. 12 the laser cavity mirrors comprisecoatings 124, 126, applied to ends of the crystal element and which havethe desired reflectivity characteristics. In a preferred embodiment anEr:YAG crystal is grown in a boule two inches in diameter and fiveinches long. The boule is core drilled to produce a rod 5-6 millimetersin diameter and five inches long. The ends of the crystal are ground andpolished. The output end, that is the end of the element from which thelaser beam exits, is perpendicular to the center axis of the rod within5 arc minutes. The flatness of the output end is {fraction (1/10)} awavelength (2.9 microns) over 90% of the aperture. The high reflectanceend, that is the end opposite the output end, comprises a two meterconvex spherical radius. The polished ends are polished so that thereare an average of ten scratches and five digs per Military SpecificationMil-0-13830A. Scratch and dig are subjective measurements that measurethe visibility of large surface defects such as defined by U.S. militarystandards. Ratings consist of two numbers, the first being thevisibility of scratches and the latter being the count of digs (smallpits). A #10 scratch appears identical to a 10 micron wide standardscratch while a #1 dig appears identical to a 0.01 mm diameter standardpit. For collimated laser beams, one normally would use optics withbetter than a 40-20 scratch-dig rating.

[0161] Many coatings are available from Rocky Mountain Instruments,Colorado Springs, Colo. The coating is then vacuum deposited on theends. For a 2.9 micron wavelength the coatings for the rear mirroredsurface 124 should have a reflectivity of greater than 99%. The coatingfor the output end surface, by contrast, should have a reflectance ofbetween 93% and 95%, but other mirrored surfaces with reflectivity aslow as 80% are useful. Other vacuum deposited metallic coatings withknown reflectance characteristics are widely available for use withother laser wavelengths.

[0162] The general equation which defines the reflectivity of themirrors in a laser cavity necessary for the threshold for populationinversion is:

R ₁ R ₂(1−a _(L))₂exp[(g ₂₁ −I)2L]=1

[0163] where the R₁ and R₂ are the mirrors' reflectivities, aL is thetotal scattering losses per pass through the cavity, g₂₁ is the gaincoefficient which is the ratio of the stimulated emission cross sectionand population inversion density, I is the absorption of the radiationover one length of the laser cavity, and L is the length of the lasercavity. Using the above equation, one can select a coating with theappropriate spectral reflectivity from the following references. W.Driscoll and W. Vaughan, “Handbook of Optics,” ch. 8, eds., McGraw-Hill:NY (1978); M. Bass, et al., “Handbook of Optics,” ch. 35, eds., McGrawHill: NY (1995).

[0164] Optionally, as also shown in FIG. 12, the crystal element may benon-rigidly mounted. In FIG. 12 an elastomeric material O-ring 128 is ina slot in the laser head assembly housing 120 located at the highreflectance end of the crystal element. A second elastomeric materialO-ring 130 is in a second slot in the laser head assembly at the outputend of the crystal element. The O-rings contact the crystal element byconcentrically receiving the element as shown. However, elastomericmaterial of any shape may be used so long as it provides elastomericsupport for the element (directly or indirectly) and thereby permitsthermal expansion of the element. Optionally, the flash lamp 22 may alsobe non-rigidly mounted. FIG. 12 shows elastomeric O-rings 134, 136, eachin its own slot within the laser head assembly housing. In FIG. 12 theO-rings 134 and 136 concentrically receive the flash lamp. However, theflash lamp may be supported by elastomeric material of other shapes,including shapes without openings.

[0165] Optionally, as shown in FIG. 3, a diode laser 42 that produces apump-beam collinear with the long-axis of the laser crystal can be usedinstead of the flashlamp to excite the crystal. The pump-beam of thislaser is collimated with a collimating lens 44, and transmitted to theprimary laser rod through the high reflectance infrared mirror 45. Thishigh reflectance mirror allows the diode pump laser beam to betransmitted, while reflecting infrared light from the primary laser.

[0166] The Er:YAG lasing material is the preferred material for thelaser rod because the wavelength of the electromagnetic energy emittedby this laser, 2.94 microns, is very near one of the peak absorptionwavelengths (approximately 3 microns) of water. Thus, this wavelength isstrongly absorbed by water and tissue. The rapid heating of water andtissue causes perforation or alteration of the skin.

[0167] Other useful lasing material is any material which, when inducedto lase, emits a wavelength that is strongly absorbed by tissue, such asthrough absorption by water, nucleic acids, proteins or lipids andconsequently causes the required perforation or alteration of the skin(although strong absorption is not required). A laser can effectivelycut or alter tissue to create the desired perforations or alterationswhere tissue exhibits an absorption coefficient of 10-10,000 cm⁻¹.Examples of useful lasing elements are pulsed CO₂ lasers, Ho:YAG(holmium:YAG), Er:YAP, Er/Cr:YSGG (erbium/chromium:yttrium, scandium,gallium, garnet; 2.796 microns), Ho:YSGG (holmium:YSGG; 2.088 microns),Er:GGSG (erbium:gadolinium, gallium, scandium, garnet), Er:YLF(erbium:yttrium, lithium, fluoride; 2.8 microns), Trn:YAG (thulium:YAG;2.01 microns), Ho:YAG (holmium:YAG; 2.127 microns); Ho/Nd:YA103(holmium/neodymium:yttrium, aluminate; 2.85-2.92 microns), cobalt:MgF₂(cobalt:magnesium fluoride; 1.75-2.5 microns), HF chemical (hydrogenfluoride; 2.6-3 microns), DF chemical (deuterium fluoride; 3.6-4microns), carbon monoxide (5-6 microns), deep UV lasers, and frequencytripled Nd:YAG (neodymium:YAG, where the laser beam is passed throughcrystals which cause the frequency to be tripled).

[0168] Utilizing current technology, some of these laser materialsprovide the added benefit of small size, allowing the laser to be smalland portable. For example, in addition to Er:YAG, Ho:YAG lasers alsoprovide this advantage.

[0169] Solid state lasers, including but not limited to those listedabove, may employ a polished barrel crystal rod. The rod surface mayalso contain a matte finish as shown in FIG. 13. However, both of theseconfigurations can result in halo rays which surround the central outputbeam. Furthermore, an all-matte finish, although capable of diminishinghalo rays relative to a polished rod, will cause a relatively largedecrease in the overall laser energy output. In order to reduce halorays and otherwise affect beam mode, the matte finish can be present onbands of various lengths along the rod, each band extending around theentire circumference of the rod. Alternatively, the matte finish may bepresent in bands along only part of the rod's circumference. FIG. 14shows a laser crystal element in which the matte finish is present uponthe full circumference of the element along two-thirds of its length.Alternatively, as shown in FIG. 15, matte stripes may be presentlongitudinally along the full length of the rod. The longitudinalstripes may alternatively exist along only part of the length of therod, such as in stripes of various lengths. A combination of theforegoing techniques may be used to affect beam shape. Other variationsof patterns may also be employed in light of the beam shape desired. Thespecific pattern may be determined based on the starting configurationof the beam from a 100% polished element in light of the desired finalbeam shape and energy level. A complete matte finish element may also beused as the starting reference point.

[0170] For purposes of beam shape control, any surface finish of greaterthan 30 microinches is considered matte. A microinch equals onemillionth (0.000001) inch, which is a common unit of measurementemployed in establishing standard roughness unit values. The degree ofroughness is calculated using the root-mean-square average of thedistances in microinches above or below the mean reference line, bytaking the square root of the mean of the sum of the squares of thesedistances. Although matte surfaces of greater than 500 microinches maybe used to affect beam shape, such a finish will seriously reduce theamount of light energy that enters the crystal rod, thereby reducing thelaser's energy.

[0171] To remove the beam halo, a matte area of approximately 50microinches is present around the full circumference of an Er:YAG laserrod for two-thirds the length of the rod. The non-matte areas of the rodare less than 10 microinches. A baseline test of the non-matte rod canbe first conducted to determine the baseline beam shape and energy ofthe rod. The matte areas are then obtained by roughing the polishedcrystal laser rod, such as with a diamond hone or grit blaster. Thespecific pattern of matte can be determined with respect to the desiredbeam shape and required beam energy level. This results in a greatlyreduced beam halo. The rod may also be developed by core drilling aboule of crystal so that it leaves an overall matte finish and thenpolishing the desired areas, or by refining a partially matte, partiallypolished boule to achieve the desired pattern.

[0172] The beam shape of a crystal laser rod element may alternativelybe modified as in FIG. 16 by surrounding the rod 20 in a material 160which is transparent to the exciting light but has an index ofrefraction greater than the rod. Such a modification can reduce the haloof the beam by increasing the escape probability of off-axis photonswithin the crystal. This procedure may be used in place of or inaddition to the foregoing matte procedure.

[0173] The emitted laser beam is focused down to a millimeter orsubmillimeter sized spot with the use of the focusing lens 28.Consideration of laser safety issues suggests that a short focal lengthfocusing lens be used to ensure that the energy fluence rate (W/cm²) islow except at the focus of the lens where the tissue sample to beperforated or altered is positioned. Consequently, the hazard of thelaser beam is minimized.

[0174] The beam can be focused so that it is narrower along one axisthan the other in order to produce a slit-shaped perforation oralteration through the use of a cylindrical focusing lens 27. This lens,which focuses the beam along one axis, is placed in series with thetransmitting focusing lens 28. When perforations or alterations areslit-shaped, the patient discomfort or pain associated with theperforation or alteration is considerably reduced.

[0175] Optionally, the beam can be broadened, for instance through theuse of a concave diverging lens 46 (FIG. 4) prior to focusing throughthe focusing lens 28. This broadening of the beam results in a laserbeam with an even lower energy fluence rate a short distance beyond thefocal point, consequently reducing the hazard level. Furthermore, thisoptical arrangement reduces the optical aberrations in the laser spot atthe treatment position, consequently resulting in a more preciseperforation or alteration.

[0176] Also optionally, the beam can be split by means of abeam-splitter to create multiple beams capable of perforating oraltering several sites simultaneously or near simultaneously. FIG. 5provides two variations of useful beam splitters. In one version,multiple beam splitters 48 such as partially silvered mirrors, dichroicmirrors, or beam-splitting prisms can be provided after the beam isfocused. Alternatively, an acousto-optic modulator 52 can be suppliedwith modulated high voltage to drive the modulator 52 and bend the beam.This modulator is outside the laser cavity. It functions by deflectingthe laser beam sequentially and rapidly at a variety of angles tosimulate the production of multiple beams.

[0177] Portability

[0178] Currently, using a portable TRANSMEDICA™ Er:YAG laser, the unitdischarges once per 20-30 seconds. This can be increased by adding abattery and capacitor and cooling system to obtain a quicker cycle.Multiple capacitors can be strung together to get the discharge ratedown to once every 5 or 10 seconds (sequentially charging the capacitorbanks). Thus, getting a higher repetition rate than with a singlecapacitor.

[0179] The TRANSMEDICA™ Er:YAG laser incorporates a flashlamp, theoutput of which is initiated by a high-voltage pulse of electricityproduced by a charged capacitor bank. Due to the high voltages requiredto excite the flashlamp, and because the referred to version of thelaser incorporates dry cells to run (thus the charging current is muchless than a wall-plug could provide), then the capacitors take about 20seconds to sufficiently charge. Thus, if a pulse repetition rate of 1pulse/20 seconds is desirable, it would be suitable to have multiplecapacitor banks that charge sequentially (i.e. as one bank fires theflashlamp, another bank, which has been recharging, fires, and so on).Thus, the pulse repetition rate is limited only be the number ofcapacitor banks incorporated into the device (and is also limited by theefficiency of waste-heat removal from the laser cavity).

[0180] A small heater, such as a thermoelectric heater 32, is optionallypositioned at the end of the laser applicator proximal to the site ofperforation. The heater raises the temperature of the tissue to beperforated or altered prior to laser irradiation. This increases thevolume of fluid collected when the device is used for that purpose. Asuggested range for skin temperature is between 36° C. and 45° C.,although any temperature which causes vasodilation and the resultingincrease in blood flow without altering the blood chemistry isappropriate.

[0181] Container Unit

[0182] A container unit 68 is optionally fitted into the laser housingand is positioned proximal to the site of irradiation. The containerunit reduces the intensity of the sound produced when the laser beamperforates the patient's tissue, increases the efficiency ofinterstitial fluid collection, and collects the ablated tissue and othermatter released by irradiation. The container unit is shaped so as toallow easy insertion into the laser housing and to provide a frictionfit within the laser housing. FIG. 8 shows the container unit insertedinto the laser housing and placed over the site of irradiation.

[0183] The container unit 68 comprises a main receptacle 82, including alens 84. The main receptacle collects the interstitial fluid sample, theablated tissue, and/or other matter released by irradiation. The lens isplaced such that the laser beam may pass through the lens to the site ofirradiation but so that the matter released by irradiation does notsplatter back onto the applicator. The container unit also optionallyincludes a base 86, attached to the receptacle. The base can optionallybe formed so at to be capable of being inserted into the applicator todisengage a safety mechanism of the device, thereby allowing the laserbeam to be emitted.

[0184] As shown in FIG. 17, the shape and size of the container unit 68are such as to allow placement next to or insertion into the applicator,and to allow collection of the interstitial fluid sample, ablatedtissue, and/or other matter released by irradiation. Examples of shapesthat the main receptacle may take include cylinders, bullet shapes,cones, polygons and free form shapes. Preferably, the container unit hasa main receptacle, with a volume of around 1-2 milliliters. However,larger and smaller receptacles will also work.

[0185] The lens 84, which allows the laser beam to pass through whilepreventing biological and other matter from splattering back onto theapplicator, is at least partially transparent. The lens is constructedof a laser light-transmitting material and is positioned in the pathwayof the laser beam, at the end of the container unit proximal to thebeam. In one embodiment, the transmitting material is quartz, but otherexamples of suitable infrared materials include rock salt, germanium,and polyethylene. As shown in FIG. 20, the lens may optionally include amask of non-transmitting material 85 such that the lens may shape theportion of the beam that is transmitted to the site of irradiation.

[0186] The main receptacle 82 is formed by the lens and a wall 88,preferably extending essentially away from the perimeter of the lens.The open end of the main receptacle or rim 90 is placed adjacent to thesite of irradiation. The area defined by the lens, wall of the mainreceptacle and the site of irradiation is thereby substantially enclosedduring the operation of the laser perforator device.

[0187] The base 86 is the part of the container unit that can optionallybe inserted into the applicator. The base may comprise a cylinder, aplurality of prongs or other structure. The base may optionally havethreading. Optionally, the base, when fully inserted, disengages asafety mechanism of the laser perforator device, allowing the emissionof the laser beam.

[0188] As shown in FIG. 19, the container unit may also include anadditional vessel 92 which collects a portion of the matter released aspart of irradiation. For example, this vessel can collect interstitialfluid and/or other liquid or particulate matter, while the mainreceptacle 82 collects the ablated tissue. The interstitial fluid and/orother liquid or particulate matter may be channeled into the vesselthrough a capillary tube 94 or other tubing which extends from the mainreceptacle into the vessel. The vessel is optionally detachable. Themain receptacle may have a hole 95 in the wall through which thecapillary tube or other tubing may be securely inserted. The vessel mayhave a removable stop 96 which sufficiently covers the open end of thevessel to prevent contamination with undesired material, but has anopening large enough for the capillary tube or other tubing to beinserted. In the preferred embodiment, the capillary tube or othertubing will extend outwardly from the main receptacle's wall and intothe vessel through the removable stop. Once the sample has beencollected, the stop may optionally be removed and discarded. The vesselmay then optionally be sealed with a cap 98 to prevent spillage. Thevessel is preferably bullet shaped.

[0189] In the first embodiment, the container unit comprises acylindrical main receptacle 82, a cylindrical base 86, and an at leastpartially transparent circular lens 84 in the area between the mainreceptacle and base. Optionally, the lens may include a mask whichshapes the beam that perforates the tissue. The container unit isconstructed of glass or plastic. The container unit is optionallydisposable.

[0190] In the second embodiment, the container unit comprises theelements of the first embodiment and also includes an additional vessel92 and a capillary tube 94 extending outwardly from the mainreceptacle's wall 88 and into the vessel through a removable stop 96.The vessel may optionally have a cap 98 to seal the opening so as toprevent spillage. The container unit is constructed of glass or plastic.The container unit, including the capillary tube and the additionalvessel, are optionally disposable.

[0191]FIG. 19 shows examples of the use of the container unit with thelaser perforator device. In this embodiment the applicator 30 issurrounded by the housing 34. The container unit is inserted in theapplicator 30 and aligned so as to be capable of defeating the interlock36. The base 86 of the container unit in this embodiment is within theapplicator 30, while the rim 90 of the receptacle 82 is located adjacentto the tissue to be perforated. The beam passes through the lens 84.

[0192] In a third embodiment, the container unit is evacuated. Theoptional vacuum in the container unit exerts a less than interstitialfluid or pressure of gases in the blood over the site of irradiation,thereby increasing the efficiency of interstitial fluid collection. Thecontainer unit's end proximal to the site of irradiation is optionallysealed air-tight with a plug 70. The plug is constructed of material ofsuitable flexibility to conform to the contours of the site ofirradiation (e.g., the finger). The desired site of irradiation isfirmly pressed against the plug. The plug's material is impermeable togas transfer. Furthermore, the plug's material is thin enough to permitperforation of the material as well as irradiation of the skin by thelaser. In the preferred embodiment, the plug is constructed of rubber.

[0193] The plug perforation center 74, as shown in FIG. 9, is preferablyconstructed of a thin rubber material. The thickness of the plug is suchthat the plug can maintain the vacuum prior to perforation, and thelaser can perforate the plug and irradiate the tissue adjacent to theplug. For use with an Er:YAG laser, the plug should be in the range ofapproximately 100 to 500 microns thick, but at the most 1 millimeterthick.

[0194] The plug perforation center 74 is large enough to cover the siteof irradiation. Optionally, the perforated site is a round hole with anapproximate diameter ranging from 0.1-1 mm, or slit shaped with anapproximate width of 0.05-0.5 mm and an approximate length up to 2.5 mm.Thus, the plug perforation center is sufficiently large to coverirradiation sites of these sizes.

[0195] The site of irradiation is firmly pressed against the rubbermaterial. Optionally, an annular ring of adhesive can be placed on therubber plug to provide an air-tight seal between the site of irradiationand the container unit. Preferably the perforation site on the plug isstretched when the tissue is pressed against the plug. This stretchingof the plug material causes the hole created in the plug to expandbeyond the size of the hole created in the tissue. As a result, theinterstitial fluid can flow unimpeded into the container unit 68. Thelaser beam penetrates the container unit, perforates the plugperforation center 74 and irradiates the patient's tissue.

[0196] In a fourth embodiment of the container unit, as shown in FIG.10, the container unit 68 includes a hole 76 through which the laserpasses. In this fourth embodiment, the container unit optionally solelycollects ablated tissue. As in the other embodiments, the site ofirradiation is firmly pressed against the container unit. The containerunit can optionally include a plug proximal to the site of irradiation,however it is not essential because there is no need to maintain avacuum in this embodiment. All embodiments of the container unit reducethe noise created from interaction between the laser beam and thepatient's tissue and thus alleviate the patient's anxiety and stress.

[0197] The container may also be modified to hold, or receive through anopening, a pharmaceutical or other substance, which may then bedelivered shortly after testing of interstitial fluid. FIG. 11 shows anexample of a container with a built-in drug reservoir and roll-onapparatus for delivery. FIG. 18 shows a container with an applicatorwhich in turn comprises an atomizer with attached high pressure gascylinder.

[0198] Optionally, the container unit is disposable, so that thecontainer unit and plug can be discarded after use. Additionally, themain receptacle of the container unit, capillary tube and/or additionalvessel can contain reagents for various tests to be performed on thecollected interstitial fluid, such as the glucose oxidase test describedabove. The reagents are positioned so that they will not be in thepathway of the laser light. The reagents are preferably present in a dryform, coating the interior walls of the collection part of the containerunit, and thus readily available for interaction with the interstitialfluid sample as it is collected.

[0199] A preferable configuration for the container unit when itcontains a regent is shown in FIG. 39. In this configuration, thecontainer unit has an indentation 78 at the base such that any fluidreagent present in the container unit will not fall into the line offire of the laser beam when the container unit is held either verticallyor horizontally. The apex 80 of the indented are is made of aninfrared-transparent substance, such as quartz, or a near transparentsubstance.

[0200] When reagents are present in the container unit prior tocollection of the interstitial fluid sample, it is beneficial to labelthe container unit in some manner as to the reagents contained inside,or as to the test to be performed on the sample using those reagents. Apreferred method for such labelling is through the use of color-codedplugs. For example, a blue plug might indicate the presence of reagentA, while a red plug might indicate the presence of reagents B plus Cwithin the container unit.

[0201] Modulated Laser

[0202] In addition to the pulsed lasers listed above, a modulated lasercan be used to duplicate a pulsed laser for the purpose of enhancingtopical drug delivery, as well as enhancing the removal of fluids. Thisis accomplished by chopping the output of the continuous-wave laser byeither modulating the laser output mechanically, optically or by othermeans such as a saturable absorber. (See, e.g., Jeff Hecht, The LaserGuidebook, McGraw-Hill:NY, 1992). Examples of continuous-wave lasersinclude CO₂, which lases over a range between 9-11 microns (e.g.Edinburgh Instruments, Edinburgh, UK), Nd:YAG, Thallium:YAG (Tm:YAG),which lases at 2.1 microns (e.g. CLR Photonics Inc., Boulder Colo.),semiconductor (diode) lasers which lase over a range from 1.0-2.0microns (SDL Inc., San Jose, Calif.).

[0203] The chopping of the laser output (for example, with a mechanicalchopper from Stanford Research Instruments Inc., Sunnyvale Calif.) willpreferably result in discrete moments of irradiation with temporalwidths from a few tenths of milliseconds, down to nanoseconds orpicoseconds. Alternatively, in the case of diode lasers, the lasingprocess can be modulated by modulating the laser excitation current. Amodulator for a laser diode power supply can be purchased from SDL Inc.,San Jose, Calif. Alternatively, the continuous-wave beam can beoptically modulated using, for example, an electro-optic cell (e.g. fromNew Focus Inc., Santa Clara, Calif.) or with a scanning mirror fromGeneral Scanning, Inc., Watertown Mass.

[0204] The additive effect of multiple perforations or alterations maybe exploited with diode lasers. Laser diodes supplied by SDL Corporation(San Jose, Calif.) transmit a continuous beam of from 1.8 to 1.96 micronwavelength radiant energy. These diodes operate at up to 500 mW outputpower and may be coupled to cumulatively produce higher energies usefulfor stratum corneum ablation. For example, one diode bar may contain tensuch diodes coupled to produce pulsed energy of 5 mJ per millisecond. Ithas been shown that an ablative effect may be seen with as little as 25mJ of energy delivered to a 1 mm diameter spot. Five (5) millisecondpulses or (25) one millisecond pulses from a diode laser of this typewill thus have an ablative effect approximately equivalent to one 25 mJpulse in the same time period.

[0205] The following examples are descriptions of the use of a laser toincrease the permeability of the stratum corneum for the purpose ofdrawing fluids, as well as for pharmaceutical delivery. These examplesare not meant to limit the scope of the invention, but are merelyembodiments.

EXAMPLE 1

[0206] The laser comprises a flashlamp (PSC Lamps, Webster, N.Y.), anEr:YAG crystal (Union Carbide Crystal Products, Washagoul, Wash.),optical-resonator mirrors (CVI Laser Corp., Albuquerque, N. Mex.), aninfrared transmitting lens (Esco Products Inc., Oak Ridge, N.J.), aswell as numerous standard electrical components such as capacitors,resistors, inductors, transistors, diodes, silicon-controlledrectifiers, fuses and switches, which can be purchased from anyelectrical component supply firm, such as Newark Electronics, LittleRock, Ark.

EXAMPLE 2

[0207] An infrared laser radiation pulse was formed using a solid state,pulsed, Er:YAG laser consisting of two flat resonator mirrors, an Er:YAGcrystal as an active medium, a power supply, and a means of focusing thelaser beam. The wavelength of the laser beam was 2.94 microns. Singlepulses were used.

[0208] The operating parameters were as follows: The energy per pulsewas 40, 80 or 120 mJ, with the size of the beam at the focal point being2 mm, creating an energy fluence of 1.27, 2.55 or 3.82 J/cm². The pulsetemporal width was 300 μs, creating an energy fluence rate of 0.42, 0.85or 1.27×10⁴ W/cm².

[0209] Transepidermal water loss (TEWL) measurements were taken of thevolar aspect of the forearms of human volunteers. Subsequently theforearms were positioned at the focal point of the laser, and the laserwas discharged. Subsequent TEWL measurements were collected from theirradiation sites, and from these the measurements of unirradiatedcontrols were subtracted. The results (shown in FIG. 27) show that atpulse energies of 40, 80 and 120 mJ, the barrier function of the stratumcorneum was reduced and the resulting water loss was measured to be 131,892 and 1743 gm/m²/hr respectively. The tape stripe positive control (25pieces of Scotch Transpore tape serially applied and quickly removedfrom a patch of skin) was measured to be 9.0 gm/m2/hr, greater thanuntouched controls; thus the laser is more efficient at reducing thebarrier function of the stratum corneum than tape-stripping.

[0210] Clinical assessment was conducted 24 hours after irradiation.Only a small eschar was apparent on the site lased at high energy, andno edema was present. None of the volunteers experienced irritation orrequired medical treatment.

EXAMPLE 3

[0211] An infrared laser radiation pulse was formed using a solid state,pulsed, Er:YAG laser consisting of two flat resonator mirrors, an Er:YAGcrystal as an active medium, a power supply, and a means of focusing thelaser beam. The wavelength of the laser beam was 2.94 microns. A singlepulse was used.

[0212] The operating parameters were as follows: The energy per pulsewas 60 mJ, with the size of the beam at the focal point being 2 mm,creating an energy fluence of 1.91 J/cm². The pulse temporal width was300 μs, creating an energy fluence rate of 0.64×10⁴ W/cm².

[0213] The volar aspect of the forearm of a volunteer was placed at thefocal point of the laser, and the laser was discharged. After dischargeof the laser, the ablated site was topically administered a 30% liquidlidocaine solution for two minutes. A 26 G-0.5 needle was subsequentlyinserted into the laser ablated site with no observable pain.Additionally, after a 6 minute anesthetic treatment, a 22 G-1 needle wasfully inserted into the laser ablated site with no observable pain. Thevolunteer experienced no irritation and did not require medicaltreatment.

EXAMPLE 4

[0214] Ablation threshold energy: Normally hydrated (66%) stratumcorneum was sandwiched between two microscope cover slides, and exposedto a single pulse of irradiation from the Er:YAG laser. Evidence ofablation was determined by holding the sample up to a light and seeingwhether any stratum corneum was left at the irradiated site. From thisexperiment, it was determined that the irradiation threshold energy (fora 2 mm irradiation spot) was approximately 90-120 mJ. The threshold willlikely be higher when the stratum corneum is still overlying epidermis,as in normal skin, since it takes energy to remove the stratum corneumfrom the epidermis, to which it is adherent.

EXAMPLE 5

[0215] Differential Scanning Calorimetry (DSQ: FIG. 28 shows a DSC scanof normally hydrated (66%) human stratum corneum, and a scan of stratumcorneum irradiated with the Er:YAG laser using a subablative pulseenergy of 60 mJ. Defining the thermal transition peaks at approximately65, 80 and 92° C., we determined the heat of transition (μJ), center ofthe transition (° C.) and the full-width at half-maximum of thetransition (° C.) (FIGS. 29-31). The results shown are on normal 66%hydrated stratum corneum, dehydrated 33% stratum corneum, steam heatedstratum corneum, Er:YAG laser irradiated stratum corneum, or stratumcorneum that was immersed in chloroform-methanol (a lipid solvent), orbeta-mercaptoethanol (a protein denaturant). The effect of laserirradiation on stratum corneum is consistent (depending on whichtransition you look at, 1, 2 or 3) with changes seen due to thermaldamage (i.e. heated with steam), and de-lipidization. Permeation with(3H₂O) and transepidermal impedance experiments on skin treated the sameway showed that the result of these treatments (heat, solvent ordenaturant) resulted in increased permeation. Thus, the changes inducedin the stratum corneum with these treatments, changes which areconsistent with those seen in laser irradiated stratum corneum, andchanges which do not result in stratum corneum ablation, result inincreased permeation.

EXAMPLE 6

[0216] Fourier Transform Infrared (FTIR) Spectroscopy: FTIR spectroscopywas used to study stratum corneum treated the same way as in the aboveDSC experiments, except the energy used was between 53 and 76 mJ. Thespectra (see, e.g., FIGS. 32-33) show that absorption bands that are dueto water, proteins and lipids change when the stratum corneum isirradiated. Some of these changes are consistent with changes seenduring non-laser treatment of the stratum corneum (e.g. desiccation,thermal damage, lipid solubilization, or protein denaturation). Forexample, the Amide I and II bands, which are due to the presence ofproteins (most likely keratin, which makes up the bulk of protein instratum corneum), shift to a larger wavenumber, consistent with theeffect of desiccation alone (in the case of Amide II) or desiccation andbeta-mercaptoethanol treatment (in the case of Amide I) (see, e.g., FIG.34). The CH2 vibrations (due to bonds in lipids) always shift to asmaller wavenumber indicating that either the intermolecular associationbetween adjacent lipid molecules has been disturbed and/or theenvironment around the lipid molecules has changed in such a way thatthe vibrational behavior of the molecules changes (see, e.g., FIG. 35).

EXAMPLE 7

[0217] Histology: Numerous in vivo experiments have been done on ratsand humans. Usually, the skin is irradiated with the Er:YAG laser and a2 mm spot and with a particular pulse energy, and then the irradiatedsite is biopsied immediately or 24 hours later. Two examples of typicalresults are shown in FIGS. 36 and 37. FIG. 36 shows rat skin irradiatedat 80 mJ, which is an energy sufficient to make the skin permeable (tolidocaine, for instance) and yet does not show any sign of stratumcorneum ablation. FIG. 37 depicts human skin 24 hours after beingirradiated at 80 mJ. In this case, some change in the appearance of thestratum corneum has taken place (perhaps coagulation of some layers ofstratum corneum into a darkly staining single layer), and yet thestratum corneum is still largely intact and is not ablated. Irradiationof human skin, in vivo, and subsequent examination under a dissectionmicroscope, show that at subablative energies (less than about 90-120mJ), the stratum corneum is still present on the skin. The irradiatedstratum corneum appears slightly whitened in vivo, which might beevidence of desiccation or separation of the stratum corneum from theunderlying tissue.

EXAMPLE 8

[0218] One way to quantify the reduction in the barrier function of thestratum corneum is to measure the reduction in the electrical impedanceof the skin as a consequence of laser irradiation. In this experiment,separate 2 mm spots on the volar aspect of the forearm of a humanvolunteer were irradiated with a single pulse of radiant energy from theEr:YAG laser using a range of energies. An ECG electrode was then placedover the irradiated site and an unirradiated site about 20 cm away onthe same forearm. A 100 Hz sine wave of magnitude 1 volt peak-to-peakwas then used to measure the impedance of the skin. The results of aseries of measurements are shown in FIG. 22, which shows that there is adecrease in skin impedance in skin irradiated at energies as low as 10mJ, using the fitted curve to interpolate data.

EXAMPLE 9

[0219] Pieces of human skin were placed in diffusion cells andirradiated with a single pulse of radiant energy produced by an Er:YAGlaser. The spot size was 2 mm and the energy of the pulse was measuredwith a calibrated energy meter. After irradiation, the diffusion cellswere placed in a 37 degrees Celsius heating block. Phosphate bufferedsaline was added to the receptor chamber below the skin and a small stirbar was inserted in the receptor chamber to keep the fluid continuallymixed. Control skin was left unirradiated. Small volumes ofradiolabelled compounds (either corticosterone or DNA) were then addedto the donor chamber and left for 15 minutes before being removed (inthe case of corticosterone) or were left for the entire duration of theexperiment (in the case of the DNA). Samples were then taken from thereceptor chamber at various times after application of the test compoundand measured in a scintillation or gamma counter. The results of thisexperiment are shown in FIGS. 21 and 26. The results illustrate thatenhanced permeation can occur at sub-ablative laser pulse energies (seethe 77 mJ/pulse data for corticosterone). Although, in the case of theDNA experiment the energy used may have been ablative, enhancedpermeation may still occur when lower energies are used.

EXAMPLE 10

[0220] Histology studies on rat and human skin, irradiated either invivo or in vitro, show little or no evidence of ablation when Er:YAGlaser pulse energies less than about 100-200 mJ are used. (See, e.g.,FIG. 25). Repeating this study showed the same results as the previousstudies. An in vitro permeation study using tritiated water (3H₂O)involving human skin lased at energies from 50 mJ (1.6 J/cm²) to 1250 mJ(40 J/cm²) determined (FIGS. 23 and 24) that an increase in permeationwas seen at low energy fluences up to about 5 J/cm², whereupon thepermeation is more-or-less constant. This shows that there has been alased induced enhancement of permeation (of tritiated water) at energiesthat are sub-ablative.

EXAMPLE 11

[0221] The output of the Er:YAG laser was passed through an aperture todefine it's diameter as 2 mm. Human skin, purchased from a skin bank,was positioned in Franz diffusion cells. The receptor chamber of thecell was filled with 0.9% buffered saline. A single pulse, of measuredenergy, was used to irradiate the skin in separate diffusion cells.Control skin was left unirradiated. In the case of insulin, a 274 mJpulse was used, and multiple samples were irradiated. After irradiation,a stirring magnet was place in the receptor chamber of the diffusioncells and the cells were placed in a heating block held at 37 □C. Theradiolabelled insulin was diluted in buffered saline, and 100 μL of theresulting solutions was placed in the donor chamber of separatediffusion cells. The donor was left on the skin for the duration of theexperiment. At various times post-drug-application, samples were takenfrom the receptor chamber and the amount of drug present was assayedwith either a gamma-counter, or a liquid scintillation counter. A graphof the resulting data is shown in FIG. 40. From this, and similar data,the permeability constant (K_(p)) for insulin was derived to be 11.3#≡˜0.93 (×10⁻³ cm/hr).

EXAMPLE 12

[0222] This data was collected during the same experiment as the TEWLresults (see Example 2 and FIG. 27). In the case of the blanching assay,baseline skin color (redness) measurements were then taken of each spotusing a Minolta CR-300 Chromameter (Minolta Inc., NJ). The Er:YAG laserwas then used to ablate six 2 mm spots on one forearm, at energies of40, 80 and 120 mJ. A spot (negative calorimeter control) directlyadjacent to the laser irradiated spots remained untouched. Subsequently,a thin film of 1% hydrocortisone ointment was applied to six of thelased spots on the treatment arm. One untouched spot on thecontralateral arm was administered a thin layer of Diprolene(□-methasone), which is a strong steroid that can permeate the intactstratum corneum in an amount sufficient to cause measurable skinblanching. An occlusive patch, consisting of simple plastic wrap, wasfixed with gauze and dermatological tape over all sites on both arms andleft in place for two hours, after which the administered steroids weregently removed with cotton swabs. Colorimeter measurements were thentaken over every unirradiated and irradiated spot at 2, 4, 8, 10, 12 and26 hours post-irradiation, these results are shown in FIG. 38. Finally,the skin was clinically assessed for evidence of irritation at the 26hour evaluation.

[0223] The results of the chromameter measurements show that someerythema (reddening) of the skin occurred, but because of theopposite-acting blanching permeating hydrocortisone, the reddening wasless than that seen in the control spots which did not receivehydrocortisone. The Diprolene control proved the validity of themeasurements and no problems were seen in the volunteers at the 26 hourevaluation, although in some of the cases the site of irradiation wasapparent as a small red spot.

EXAMPLE 13

[0224] The radiant output of the Er:YAG laser is focussed and collimatedwith optics to produce a spot size at the surface of the skin of, forexample, 5 mm. The skin of the patient, being the site of, or close tothe site of, disease, is visually examined for anything that mightaffect the pharmacokinetics of the soon to be administered drug (e.g.,significant erythema or a wide-spread loss of the integrity of thestratum corneum). This site, which is to be the site of irradiation, isgently cleansed to remove all debris and any extraneous compounds suchas perfume or a buildup of body oils. A disposable tip attached to thelaser pressed up to the skin prior to irradiation is used to contain anyablated biological debris, as well as to contain any errant radiantenergy produced by the laser. A single laser pulse (approximately 350 μslong), with an energy of 950 mJ, is used to irradiate the spot. Theresult is a reduction or elimination of the barrier function of thestratum corneum. Subsequently, an amount of pharmaceutical,hydrocortisone for example, is spread over the irradiation site. Thepharmaceutical may be in the form of an ointment so that it remains onthe site of irradiation. Optionally, an occlusive patch is placed overthe drug in order to keep it in place over the irradiation site.

[0225] While various applications of this invention have been shown anddescribed, it should be apparent to those skilled in the art that manymodifications of the described techniques are possible without departingfrom the inventive concepts herein.

We claim:
 1. A method of measuring analyte concentrations in bodilyfluids, comprising the steps of: a) focusing a laser beam withsufficient energy fluence to ablate the skin at least as deep as thestratum corneum, but not as deep as the capillary layer; b) firing thelaser to create a site of ablation, the site having a diameter ofbetween 0.5 microns and 5.0 cm; c) collecting a sample of interstitialfluid released by steps (a) and (b); and d) testing the interstitialfluid for analyte concentration.
 2. The method of claim 1 wherein thelaser beam has a wavelength of 0.2-10 microns.
 3. The method of claim 1wherein the laser beam has a wavelength of between 1.5-3.0 microns. 4.The method of claim 1 wherein the laser beam has a wavelength of about2.94 microns.
 5. The method of claim 1 wherein the laser beam is emittedby a laser selected from the group consisting of Er:YAG, pulsed CO₂,Ho:YAG, Er:YAP, Er/Cr:YSGG, Ho:YSGG, Er:GGSG, Er:YLF, Tm:YAG, Ho:YAG,Ho/Nd:Yalo₃, cobalt:MgF2, HF chemical, DF chemical, carbon monoxide,deep UV lasers, and frequency tripled Nd:YAG lasers.
 6. The method ofclaim 1 wherein the laser beam is emitted by an Er:YAG laser.
 7. Themethod of claim 1 wherein the laser beam is emitted by a modulated laserselected from the group consisting of continuous-wave CO₂, Nd:YAG,Thallium:YAG and diode lasers.
 8. The method of claim 1 wherein thelaser beam is focused at a site on the skin with a diameter of 0.1-5.0mm.
 9. The method of claim 1 wherein the energy fluence of the laserbeam at the skin is 0.03-100,000 J/cm².
 10. The method of claim 1wherein the energy fluence of the laser beam at the skin is 0.03-9.6J/cm².
 11. The method of claim 1 wherein multiple ablations are made toprepare the skin for diffusion of interstitial fluid.
 12. The method ofclaim 1 wherein multiple ablations are made to prepare the skin forpharmaceutical delivery.
 13. The method of claim 1 further comprising abeam splitter positioned to create, simultaneously from the laser,multiple sites of ablation.
 14. The method of claim 13 wherein the beamsplitter is selected from a series of partially silvered mirrors, aseries of dichroic mirrors, and a series of beam-splitting prisms. 15.The method of claim 1 further comprising an acousto-optic modulatoroutside the laser cavity wherein the modulator consecutively deflectsthe beam at different angles to create different sites of ablation onthe skin.
 16. The method of claim 1 wherein the analyte to be measuredis selected from the group consisting of Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺, Cl⁻, HCO₃⁻, HHCO3, phosphates, S4, glucose, ammo acid, cholesterol,phospholipids, neutral fat, PO₂ ⁻, pH, organic acids or proteins. 17.The method of claim 1 wherein the analyte measurement is used torepresent the analyte concentration in blood.
 18. The method of claim 1wherein the interstitial fluid is collected in a container positionedproximal to the ablation site and through which the laser beam passes.19. The method of claim 18 wherein the testing of analyte concentrationis conducted while the container unit is attached to the laser device.20. The method of claim 1 further comprising the step of applying atherapeutically effective amount of a pharmaceutical composition at thesite of ablation.
 21. The method of claim 20 wherein the pharmaceuticalsubstance is administered based on analyte concentration in theinterstitial fluid.
 22. The method of claim 1 further comprising thestep of applying a pressure gradient to the skin after formation of thesite of ablation to increase the diffusion rate of interstitial fluid.23. The method of claim 1 further comprising the step of mechanicallyincreasing the diffusion rate of interstitial fluid after formation of asite of ablation.
 24. The method of claim 23 wherein diffusion isincreased by the application of subatmospheric pressure at the ablationsite.
 25. The method of claim 24 wherein the container unit is undersubatmospheric pressure.
 26. The method of claim 1 wherein a pressuregradient is created at the site of ablation to increase the removal ofbodily fluids.
 27. A method of measuring analyte concentrations inbodily fluids, comprising the steps of: a) focusing a laser beam withsufficient energy fluence to alter the skin at least as deep as thestratum corneum, but not as deep as the capillary layer; and b) firingthe laser to create a site of alteration, the site having a diameter ofbetween 0.5 microns and 5.0 cm. c) collecting a sample of interstitialfluid released by steps (a) and (b); and d) testing the fluid foranalyte concentration.
 28. The method of claim 27 wherein the laser beamhas a wavelength of 0.2-10 microns.
 29. The method of claim 27 whereinthe laser beam has a wavelength of between 1.5-3.0 microns.
 30. Themethod of claim 27 wherein the laser beam has a wavelength of about 2.94microns.
 31. The method of claim 27 wherein the laser beam is emitted bya laser selected from the group consisting of Er:YAG, pulsed CO₂,Ho:YAG, Er:YAP, Er/Cr:YSGG, Ho:YSGG, Er:GGSG, Er:YLF, Tm:YAG, Ho:YAG,Ho/Nd:Yalo₃, cobalt:MgF2, HF chemical, DF chemical, carbon monoxide,deep UV lasers, and frequency tripled Nd:YAG lasers.
 32. The method ofclaim 27 wherein the laser beam is emitted by an Er:YAG laser.
 33. Themethod of claim 27 wherein the laser beam is emitted by a modulatedlaser selected from the group consisting of continuous-wave CO₂, Nd:YAG,Thallium:YAG and diode lasers.
 34. The method of claim 27 wherein thelaser beam is focused at a site on the skin with a diameter of 0.1-5.0mm.
 35. The method of claim 27 wherein the energy fluence of the laserbeam at the skin is 0.03-100,000 J/cm².
 36. The method of claim 27wherein the energy fluence of the laser beam at the skin is 0.03-9.6J/cm².
 37. The method of claim 27 wherein multiple alterations are madeto prepare the skin for diffusion of interstitial fluid.
 38. The methodof claim 27 wherein multiple alterations are made to prepare the skinfor pharmaceutical delivery.
 39. The method of claim 27 furthercomprising a beam splitter positioned to create, simultaneously from thelaser, multiple sites of alteration.
 40. The method of claim 39 whereinthe beam splitter is selected from a series of partially silveredmirrors, a series of dichroic mirrors, and a series of beam-splittingprisms.
 41. The method of claim 27 further comprising an acousto-opticmodulator outside the laser cavity wherein the modulator consecutivelydeflects the beam at different angles to create different sites ofalteration on the skin.
 42. The method of claim 27 wherein the analyteto be measured is selected from the group consisting of Na⁺, K⁺, Ca⁺⁺,Mg⁺⁺, Cl⁻, HCO3, HHCO3, phosphates, S4⁻, glucose, amino acid,cholesterol, phospholipids, neutral fat, PO2⁻, pH, organic acids orproteins.
 43. The method of claim 27 wherein the analyte measurement isused to represent the analyte concentration in blood.
 44. The method ofclaim 27 wherein the interstitial fluid is collected in a containerpositioned proximal to the ablation site and through which the laserbeam passes.
 45. The method of claim 27 wherein the testing of analyteconcentration is conducted while the container unit is attached to thelaser device.
 46. The method of claim 27 further comprising the step ofapplying a therapeutically effective amount of a pharmaceuticalcomposition at the site of alteration.
 47. The method of claim 46wherein the pharmaceutical substance is administered based on analyteconcentration in the interstitial fluid.
 48. The method of claim 27further comprising the step of applying a pressure gradient to the skinafter formation of the site of ablation to increase the diffusion rateof interstitial fluid.
 49. The method of claim 27 further comprising thestep of mechanically increasing the diffusion rate of interstitial fluidafter formation of a site of alteration.
 50. The method of claim 49wherein diffusion is increased by the application of sub-atmosphericpressure at the alteration site.
 51. The method of claim 50 wherein thecontainer unit is under subatmospheric pressure.
 52. The method of claim27 wherein a pressure gradient is created at the site of alteration toincrease the removal of bodily fluids.
 53. A method of measuring analyteconcentration in bodily fluids, comprising the steps of: a) applyingsub-atmospheric pressure at the surface of the skin to induce theformation of a microblister; b) focusing a laser beam with sufficientenergy fluence to lyse a microblister; c) firing the laser to lyse theblister; d) collecting a sample of interstitial fluid released by steps(a), (b) and (c); and e) testing the fluid for analyte concentration.54. The method of claim 53 wherein the laser beam has a wavelength of0.2-10 microns.
 55. The method of claim 53 wherein the laser beam has awavelength of between 1.5-3.0 microns.
 56. The method of claim 53wherein the laser beam has a wavelength of about 2.94 microns.
 57. Themethod of claim 53 wherein the laser beam is emitted by a laser selectedfrom the group consisting of Er:YAG, pulsed CO₂ Ho:YAG, Er:YAP,Er/Cr:YSGG, Ho:YSGG, Er:GGSG, Er:YLF, Tm:YAG, Ho:YAG, Ho/Nd:Yalo₃,cobalt:MgF2, HF chemical, DF chemical, carbon monoxide, deep UV lasers,and frequency tripled Nd:YAG lasers.
 58. The method of claim 53 whereinthe laser beam is emitted by an Er:YAG laser.
 59. The method of claim 53wherein the laser beam is emitted by a modulated laser selected from thegroup consisting of continuous-wave CO₂, Nd:YAG, Thallium:YAG and diodelasers.
 60. The method of claim 53 wherein the laser beam is focused ata site on the skin with a diameter of 0.1-5.0 mm.
 61. The method ofclaim 53 wherein the energy fluence of the laser beam at the skin is0.03-100,000 J/cm².
 62. The method of claim 53 wherein the energyfluence of the laser beam at the skin is 0.03-9.6 J/cm².
 63. The methodof claim 53 wherein multiple microblisters are made for collection ofinterstitial fluid.
 64. The method of claim 53 further comprising a beamsplitter positioned to lyse, simultaneously from the laser, multiplemicroblisters.
 65. The method of claim 64 wherein the beam splitter isselected from a series of partially silvered mirrors, a series ofdichroic mirrors, and a series of beam-splitting prisms.
 66. The methodof claim 53 further comprising an acousto-optic modulator outside thelaser cavity wherein the modulator consecutively deflects the beam atdifferent angles to lyse different microblisters.
 67. The method ofclaim 53 wherein the analyte to be measured is selected from the groupconsisting of Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺, Cl⁻, HCO₃ ⁻, HHCO3, phosphates, S4⁻glucose, ammo acid, cholesterol, phospholipids, neutral fat, PO₂ ⁻, pH,organic acids or proteins.
 68. The method of claim 53 wherein theanalyte measurement is used to represent the analyte concentration inblood.
 69. The method of claim 53 wherein the interstitial fluid iscollected in a container positioned proximal to the microblister andthrough which the laser beam passes.
 70. The method of claim 53 whereinthe testing of analyte concentration is conducted whue the containerunit is attached to the laser device.
 71. The method of claim 53 furthercomprising the step of applying a therapeutically effective amount of apharmaceutical composition at the site of the lysed microblister. 72.The method of claim 71 wherein the pharmaceutical substance isadministered based on analyte concentration in the interstitial fluid.